september 29, 2023 by Paul - Legacy Tree Genealogists Researcher 2 Comments

7 Strategies to Set Up Your DNA Project for Success

DNA testing plans and knowing how to set up a DNA project for success makes all the difference in solving family tree mysteries. At Legacy Tree Genealogists, we have helped thousands of clients utilize DNA evidence in the exploration of their family history research questions. From recent unknown parentage to historic misattributed ancestry, we have observed again and again that by inviting the right people to perform DNA testing in the right DNA databases, stubborn genealogy brick walls come tumbling down.

Below are seven strategies that we have found instrumental in setting a strong foundation for the success of DNA genealogy projects.

DNA Genealogy

Prioritize the Closest Generation

Autosomal DNA tests are the most common and popular form of genetic genealogy test (23andMe, Ancestry, MyHeritageDNA, Living DNA, and the Family Finder test at FamilyTreeDNA are all autosomal DNA tests). Each individual inherits half of their autosomal DNA from each of their parents. Beyond that, the amount of DNA shared in common is only approximate due to a random process called recombination which shuffles the DNA each generation. Each individual will inherit about 25% from each grandparent, 12.5% from each great-grandparent and approximately half the previous amount for each subsequent generation. Eventually, there will be some ancestors in a person’s family history from whom they have inherited no DNA.

As a result, when trying to utilize autosomal DNA tests to explore a family history research question, it is most beneficial to prioritize the test results of the closest generation to the research subject. This approach aims to leverage the most DNA possible from an ancestral subject in order to learn more about that individual’s ancestry. The tester who is the closest generationally and who inherited the most DNA from the ancestor of interest will typically have more pertinent genetic cousins, stronger connections to those genetic cousins, and clearer indications of which pertinent genetic cousins are most important.

For example, if you are interested in learning more about the parentage of your great-grandfather, then rather than using your own test results (which would only cover about 12% of your great-grandfather’s DNA) consider using the test results of your parent (25% of the DNA of your great-grandfather), or your grandparent (50% of the DNA of your great-grandfather) if at all possible.

Have you figured out the closest generational descendant to your research subject? Have they performed DNA testing? If so, try and collaborate with them to obtain access to their DNA test results. Are you having trouble identifying the best person to use for your DNA research project? We can help with a DNA testing plan or DNA research plan.

Test Multiple Relatives

Different descendants of an ancestor inherit different parts of that individual’s autosomal DNA. Therefore, they will have different pertinent genetic cousins, different amounts of shared DNA with pertinent genetic cousins, and different segments of shared DNA with pertinent genetic cousins. By testing multiple descendants of an ancestor of interest, it is possible to leverage even more of the DNA of that deceased ancestor in the exploration of their family tree. Testing multiple descendants also helps in the later organization and sorting of DNA match lists in order to identify pertinent genetic cousins.

Do you know additional descendants of your ancestor who would be willing to perform DNA testing? Siblings? First cousins? Even more distant relatives? Have any of them already performed DNA testing? If so, be sure to recruit their help in your efforts to learn more about your shared ancestors. If possible, try to obtain access to their test results as well. Are you wondering which of your relatives or how many of them should test for your project? Let us help you prioritize your DNA testing plan.

Test for Filtering

Sometimes, testing people not related through the line of your research question can be extremely helpful for determining which matches are not pertinent (and by process of elimination which ones most likely are). This is particularly true if a research subject has few descendants (or few descendants who are willing to perform DNA testing). This approach is also particularly helpful in cases of recent unknown parentage.

For example, if you are interested in identifying your biological father, but it is not yet clear which matches are relevant, testing your mother, a maternal aunt or uncle, a maternal half sibling or a maternal first cousin (preferably someone who shares all of your maternal ancestors) could help in clarifying which shared genetic cousins are maternal relatives versus which genetic cousins are most likely paternal.

If you have some more distant known maternal relatives who have already tested, but no known maternal relatives from other ancestral lines, testing known relatives from the underrepresented lines can help ensure that you are focusing on the right people in the pursuit of your goal and not getting sidetracked by people who actually are related through a different known line.

Do you have known relatives from other ancestral lines who have performed DNA testing and who are already appearing in your match list? If not, consider testing close relatives from various branches of your family tree to help make more sense of your DNA test results. Are you not sure who would be the best test? We can help you determine if filter testing is needed for your case, and who best to test and where.

Test (or Upload) Everywhere

Several DNA testing companies sell genetic genealogy tests, and each maintains its own database of tested customers. It is never known where a key match for your case might appear, so we recommend testing everywhere possible.

AncestryDNA maintains the largest database of tested customers with over 20 million tested individuals.

23andMe maintains the second largest database with over 12 million tested customers.

MyHeritage comes in third at over 6 million and FamilyTreeDNA and LivingDNA have their own databases of between 1 and 3 million customers each.

Currently, the only way to get your DNA matched against customers at 23andMe and AncestryDNA is by testing with those companies directly. Meanwhile, FamilyTreeDNA, MyHeritage and LivingDNA accept DNA data transfers from other DNA testing companies. That means that if you have already performed a DNA test at one company, you can download your raw data, and upload that data to FamilyTreeDNA, MyHeritage or LivingDNA.

Additionally, GEDmatch, a third-party website, permits uploads of DNA data from each of the major testing companies. While uploads of data are free, accessing all of the tools provided by these companies requires payment of a subscription or an unlock fee. If uploading to some of these other sites, be sure to consider the terms of service and privacy statements. Some of these companies utilize DNA data for pursuits other than genealogical research, including criminal investigations and/or pharmaceutical research.

DNA Testing Plan

Is your DNA in each of the major DNA testing company databases (AncestryDNA, 23andMe, MyHeritage, FamilyTreeDNA, Living DNA and GEDmatch)? Beyond your own DNA, is the DNA of the closest generational descendant of your ancestor, the DNA of other descendants of your ancestor, and/or the DNA of filter testers from your other ancestral lines present in each of the major DNA testing databases? If not, consider working with your relatives to get them into every database and connect with key genetic cousins everywhere. Creating a solid DNA testing plan will help you cover all of your bases.

Are you struggling to get your DNA test results uploaded into every database, either for yourself or for a relative? We can help as part of the set up for your project.

Identify or Collaborate with Your Closest Genetic Cousins

As we begin working on DNA cases, we often find that there are close genetic cousins within the range of close family to second cousins. Sometimes these individuals have family trees, but other times the only information they have provided in connection with their test results is an ambiguous username. If you recognize any matches sharing more than 200 centimorgans (cM), make sure to take note and determine the exact nature of their relationship to you. Clarifying that information can help in interpreting all of your other DNA matches. If you are unsure of one of these match’s identity, try contacting them through the company messaging system to see how they might be related or to learn more about their family tree. Even if the nature of their relationship is unclear, getting the names of their grandparents can be a great first step to making sense of their relationship to you. Once known relatives are identified, then close unknown relatives can be prioritized for additional analysis and investigation.

Do you have any close genetic cousins sharing more than 200 cM with you who are known relatives? Are there any close relatives who you do not recognize? Let us know what you see. Telling us about your known genetic cousins helps us work more efficiently as we set up your DNA testing plan.

If you have genetic cousins you can’t quite identify, we will do our best to apply our knowledge of modern research on living individuals to determine their identity and their relationship to you. Want to learn more about how you are related to your genetic cousins? Download your free DNA & Relationships Chart here.

Don’t Forget Y-DNA and mtDNA

While autosomal DNA testing is the most common and popular form of DNA testing, and while it is often the go-to type of test for more recent research questions, it is not the only type of DNA testing that can help with family history research questions. The more historical a research question is, the more important Y-DNA and mitochondrial DNA testing become for a DNA project. While these types of tests might not be the first choice test for recent cases of unknown parentage, they are extremely important whenever they can be utilized for research questions pre-dating the late 1800s.

Males inherit Y-DNA, or the Y-chromosome, from their father, who inherited a copy of the same DNA from his father, who inherited a copy of the same DNA from his father… in a line of direct paternal inheritance. As such, Y-DNA follows the same inheritance pattern as surnames in many Western societies. Y-DNA testing can help identify candidates to be direct paternal ancestors or identify surname associations for an adoptee or historic misattributed parentage case. Advanced Y-DNA testing (like FamilyTreeDNA’s Big Y-700 test) can even distinguish between historical candidates to be the biological father of an ancestor.

All individuals inherit their mitochondrial DNA from their mother who inherited a copy of the same DNA from her mother… in a line of direct maternal inheritance. Individuals who share the same mitochondrial DNA are related along their respective direct maternal ancestral lines. However, since mitochondrial DNA mutates at a slower rate overall than Y-DNA, even exact mitochondrial DNA matches can be very distantly related. Mitochondrial DNA testing can be helpful for confirming or refuting the candidacy of hypothesized mothers of an ancestor.

Is your research question on your direct paternal line? If so, perform a Y-DNA test, or invite a brother, father, uncle, or cousin to perform a Y-DNA test at FamilyTreeDNA. Is your research question on your direct maternal line? If so, perform a mitochondrial DNA test at FamilyTreeDNA.

Consider also that even if your research question is not on your direct paternal or maternal line, it might be on the direct maternal or paternal line of one of your relatives, and it may be worth inviting them to perform that DNA test.

Reserve Budget for Additional Testing

Sometimes, testing your own DNA or the DNA of your close relatives can only get you so far. Solving a DNA research question often requires additional targeted testing of living relatives of candidate ancestors.

For example, your own DNA testing may help to identify a group of genetic cousins likely related through your unknown ancestor, and the pedigrees of those DNA matches may relate to each other in such a way that you are able to determine that the mystery biological father of your ancestor (or even yourself) was one of four brothers who all lived in the same locality as your ancestor’s mother (or your own mother). Distinguishing which candidate was most likely your own direct ancestor will require inviting those candidates (or more often their descendants) to perform DNA testing. Individuals are often more willing to perform DNA testing if the cost of testing is covered, so as you plan for the success of your research project, be sure to keep in mind that additional DNA testing expenses may be necessary to ultimately arrive at the answer and conclusion you are looking for.

Have you already narrowed your search down to some hypothesized ancestors? Let us know and we can help in your efforts to identify, contact, and recruit living relatives to perform DNA testing in order to solve your research questions.

Are you just starting your genetic genealogy journey, or you are nearing the finish line in your DNA research project? Whether you are still prioritizing your DNA testing plan, working with your DNA matches, or recruiting additional relatives to finally prove the answer to your question, we stand ready to help in any part of the process. Let us help you apply genetic genealogy to the pursuit of your family history. Contact us today for a free quote.

juni 2, 2023 by Paul - Legacy Tree Genealogists Researcher Leave a Comment

Part Two: MyHeritage DNA Theories of Family Relativity

Theories of Family Relativity is part two of a series of articles to help you navigate MyHeritage DNA matches and tools. Read part one here.

Genetic genealogy is founded on the observation that when two testers share DNA, they share common ancestry. In the case of autosomal DNA tests (like the one offered by MyHeritage), the ancestor who was the source of that shared DNA could be through any of the respective testers’ ancestral lines and could be any number of generations back in the past.

Generally, when two testers share a large amount of DNA across multiple segments, they share more recent ancestors.

Meanwhile, if two testers share a single small segment of DNA, their common ancestor may be very distant. While shared autosomal DNA points to a genealogical relationship and perhaps the approximate generational distance to the source of shared DNA, documentation of both individuals' genealogy is necessary to identify the common ancestor. Many testers are unfamiliar with the identities of their more distant ancestors and may need to learn how to extend their family trees. The Theories of Family Relativity tool at MyHeritage can help in these cases.

MyHeritage DNA Theories of Family Relativity

Census records, vital records, and compiled family trees might be used to connect the small trees started by each tester through generations of unknown ancestry. If two testers attach small family trees for the first few generations of their ancestry to their DNA test results, MyHeritage will search their extensive databases of indexed records and compiled family trees for a genealogical path connecting the two testers.

For example, if one tester reports the identity of their grandmother, then MyHeritage might find mention of that grandmother in a census record linking her to her parents. In turn, her father and his brother might be mentioned in a family tree. If the other tester reports his grandfather's identity, MyHeritage might recognize that grandfather as the same individual as the brother of the first tester’s great-grandfather.

While Theories of Family Relativity may find a proposed connection between two testers, this does not always mean that the proposed common ancestors are necessarily the source of the shared DNA between the two individuals. The shared DNA might still come from another ancestral line. Even so, Theories of Family Relativity provide clues for further evaluation. One way to evaluate a proposed relationship is to consider shared matches, and Auto Cluster reports.

MyHeritage AutoClusters Tool

When two testers share DNA, they sometimes share genetic cousins. Evaluation of lists of shared cousins between a tester and any given match can sometimes reveal the existence of clusters of genetic cousins. Together these clusters of matches form a network of genetic relationships between a tester’s matches.

Genetic networks comprise subjects, nodes (matches), edges (relationships), and clusters. The subject of a network is most often a tester; nodes in a network are the matches to a tester. Edges are the relationships between a tester’s matches. Together these relationships form clusters.

The MyHeritage AutoClusters tool, licensed by MyHeritage from GeneticAffairs creator Evert-Jan Bloom, is a form of genetic network. Matches of a test subject are listed along the matrix's right side and in the same order along the top of the matrix. Dark-colored boxes represent the intersection of a row and column associated with a single match. Light-colored boxes represent genetic relationships between genetic cousins. Relationships of the same color are grouped together in clusters.

Genetic clusters are often composed of individuals who are either:

• Descendants of a shared ancestor or ancestral couple

• Descendants of a shared ancestral couple along with some collateral relatives of both the

husband and wife in that couple.

• Members of an endogamous community.

If one of the individuals in a genetic cluster has a theory of family relativity or a known shared ancestor with a tester, it is possible that other members of the same cluster are also related through the same ancestral line.

Though genetic cousins are grouped in clusters, not all members of a cluster will necessarily be genetic cousins to all other members of the same cluster. This might happen because two members of a cluster are both descended from a common ancestor but are distant enough relatives that they do not share DNA with each other.

Alternatively, they may share a small amount of DNA. Still, they may not share enough DNA to be considered a shared match (this threshold is automatically set by MyHeritage and is described below the AutoCluster chart).

In the AutoClusters report, slightly darker colored boxes represent the intersection of a row and column dedicated to a single genetic cousin. Slightly lighter colored boxes represent genetic relationships between a tester’s matches. Tan boxes are present when a match does not share DNA (or does not share enough DNA) with another member of the cluster. Gray boxes represent relationships between genetic cousins who are members of different clusters. Along the right hand side, MyHeritage describes each cluster. Clicking on these descriptions will identify all members of the cluster.

In other situations, they may not be relatives to each other at all but may be related to most other members of the group. For example, most members of the group may descend from a common ancestral couple. Still, one member might be a collateral relative of the male common ancestor, and another member of the group may be a collateral relative of the female common ancestor.

In other cases, members of a cluster may have genetic relationships with members of other clusters. This can happen when each cluster is composed of descendants of separate ancestral couples, but one match is related as a closer relative and is descended from both ancestral couples. In other cases, a match might have independent shared ancestry with one or more genetic cousins in another cluster.

Yet, in other situations, both clusters might comprise members of the same endogamous population.

In all cases, Theories of Family Relativity and AutoClusters might be utilized to identify genetic cousins likely related through specific ancestral lines. Members of known clusters might be used to explore more distant ancestry of the corresponding ancestral couple or couples. Mystery clusters composed of genetic cousins with no known relationship to a tester but with a documented relationship to each other represent opportunities for further exploration in genetic genealogy research. Those individuals may be related through the ancestors just beyond a researcher’s brick wall!

Read Part One: Navigating MyHeritage DNA Matches and Tools here.

april 5, 2023 by Paul - Legacy Tree Genealogists Researcher 6 Comments

Autosomal DNA Test Results: Using Ethnicity Estimates to Generate Genealogical Hypotheses

The material in this autosomal DNA blog article was originally published in the October-December 2021 issue of NGS Magazine. It is updated and republished here with permission.

Autosomal DNA test results at the major genetic genealogy testing companies (23andMe, Ancestry, Family Tree DNA, LivingDNA, MyHeritage) include two main elements: ethnicity admixture estimates and genetic cousin match lists.

While genetic cousin match lists are the most helpful resource for solving genealogical problems utilizing autosomal DNA, ethnicity admixture estimates can provide important context and clues to aid the interpretation of DNA matches.

When carefully analyzed, ethnicity estimates can sometimes aid in forming hypotheses that can be tested through more in-depth research in genetic cousin match lists.

Even so, ethnicity estimates are still estimates, and will continually be refined as company reference panels and algorithms improve. These ethnicity estimates should be considered within the context of all available evidence, including genetic cousin relationships.

Basic Interpretation of Autosomal DNA Ethnicity Admixture Estimates

With few exceptions, each individual inherits 50% of their autosomal DNA from their mother in 22 chromosomes and 50% of their autosomal DNA from their father in 22 corresponding homologous chromosomes (meaning that they are similar in size, shape, and organization of genetic material). Since you can inherit only 50% of your DNA from each parent, if your ethnicity admixture estimate reports approximately 50% from one region and approximately 50% from another unique region, it could indicate that you have one parent from each region. Meanwhile, if you have significantly more than 50% admixture (more than 60-70%) from a single region, it could indicate that both of your parents had at least some ancestry from that region.

While each company can typically differentiate genetic admixture at the continental level, it is more difficult to distinguish between closely related populations.

If a test subject has significantly more than 50% admixture from a single region, it could indicate that both parents had at least some ancestry from that region. In this case, the test subject has significant British Isles ancestry on both sides of her family tree.

You can read more about understanding Autosomal DNA in our article here: How to Understand Your Closest Autosomal DNA Test Matches.

Using Caution

Even so, use caution when making these preliminary observations, particularly if your parents have ancestry from different countries in the same general area. For example, if you have one parent from Ireland and another from Japan, you will likely have a fairly even split in ethnicity admixture estimates.

Meanwhile, you have one parent from Norway and another from Germany. In that case, you may have higher than expected estimates of Scandinavian admixture, German admixture, or other populations in Northwestern Europe because of the proximity and historical association of those two populations.

These observations can help provide the context in cases of adoption, unknown parentage, or misattributed parentage, but can even be helpful for more distant genealogical research problems.

Making Sense of the %

If you have a unique ethnicity admixture region that stands out from the rest of your estimate, then the percentage might give clues to estimate the distance to the ancestral source of that DNA. Each person inherits 50% of the autosomal DNA from each parent, about 25% from each grandparent, about 12% from each great-grandparent, and about half again every generation back in time.

Therefore, if you have approximately 25% Jewish admixture, you were surprised that it might come from an unknown grandparent. If you have 4-8% Iberian admixture, it could come from a Spanish or Portuguese second great-grandparent.

However, ethnicity estimates need not originate from a single ancestor. If you have 25% Aboriginal ancestry, you could just as easily have two Aboriginal great-grandparents from different ancestral lines as a single grandparent with Aboriginal ancestry.

If a test taker’s ethnicity admixture estimate reports approximately 50% from one region and approximately 50% from another unique region, it could indicate that the test subject has one parent from each region. in this example from MyHeritage, the test taker’s mother was completely Danish fitting with her 44% Scandinavian admixture.

Using an Absence of Information to Find Answers

Even the absence of a unique admixture estimate can aid in forming hypotheses in genealogical research. For example, if you ultimately attempt to identify your unknown second great-grandfather, your DNA test results reveal you have a 100% British admixture. You could assume that your unknown second great-grandfather was also probably from the British Isles.

While we inherit autosomal DNA from many of our ancestors across many ancestral lines, not all of our distant ancestors contribute to our inherited set of DNA.

Even so, each of us should inherit at least some DNA from each of our fourth great-grandparents. Therefore, if you have a family story that your great-great-grandmother was “full-blood Cherokee,” yet you have no Native American admixture, it could indicate that your family story is inaccurate.

Want to know what to do next? You can learn more in our article Eight Steps to Pursue With New Autosomal DNA Test Results.

Ethnicity Chromosome Paintings

In July 2021, Family Tree DNA announced that they would soon be releasing a chromosome ethnicity painting. Ethnicity paintings are helpful for formulating hypotheses based on number, size and position of segments assigned to particular ethnicity regions.

In addition to ethnicity admixture estimates, 23andMe also provides an ethnicity chromosome painting showing which DNA segments correspond to different ethnicity regions. In September 2021, Family Tree DNA began offering a similar feature, and in July 2022, AncestryDNA also began providing a chromosome painting in connection with their ethnicity reports. They also began dividing ethnicity admixture estimates by parent. These representations can offer additional insights beyond the information provided by the percentage reports alone.

Autosomal DNA tests query thousands of markers across a test-takers genome and report two values for each marker: a value from the paternal chromosome and a value from the maternal chromosome. At any given site, however, it is impossible to tell which value corresponds to the maternal chromosome and which corresponds to the paternal chromosome. Further, it is difficult to determine which value on a consecutive marker corresponds with the same chromosome copy as the first or second value on the previous marker.

23andMe processes DNA data to “phase” test results to construct ethnicity chromosome paintings. Through the phasing process, 23andMe attempts to determine which consecutive markers belong with each other on one chromosome copy and which marker values belong together on the other chromosome copy. Family Tree DNA and AncestryDNA utilize similar approaches.

Want to learn more ways to use chromosome paintings? Read our article 5 Ways to Use the DNA Coverage Estimator Tool at DNA Painter.

How To Determine Maternal or Paternal Chromosomes

Once DNA test data has been phased, it is chopped into smaller chunks or windows and assigned to reference populations. The 23andMe results show these assignments in the chromosome painting. Since it is not possible to know which DNA is paternal and which is maternal without additional information, the top chromosome in each representation is not necessarily paternal. The bottom is only sometimes maternal. Further, since the DNA is chopped up before being assigned to regional categories, it is possible and often occurs that the representation of one chromosome copy is a combination of maternal and paternal DNA.

Therefore, just because a particular ethnicity admixture assignment appears on the top chromosome version in some pairs and on the bottom chromosome version in other pairs does not mean that both parents have admixture from that region.

Also, just because a particular ethnicity admixture assignment appears on the top version of a single chromosome pair and in a different region on the bottom of the same chromosome pair does not mean that both parents have admixture from that region. Even with these caveats, chromosome paintings can reveal important information regarding your ancestry.

If one complete version of every chromosome pair is assigned to one ethnic region and the other complete version of every chromosome pair is assigned to another ethnic region, it indicates that your father is of one ethnicity and your mother is of the other, rather than having a mix of ancestors from both regions on both sides of your family tree. Suppose there are several chromosomes where large overlapping regions on both chromosome copies have been assigned to the same ethnic region.

In that case, it can indicate that both of your parents have at least some ancestry from that region. If just a few large chunks of DNA are assigned to a particular ethnic region, it can suggest that you have only one (or perhaps a few) recent ancestor(s) originating from that area. Meanwhile, suppose the assignments for a unique ethnic region are dispersed across the genome in many small segments. In that case, this can indicate that you have multiple more distant ancestors from that region.

The Difference Between X-DNA, Y-DNA, and Mitochondrial DNA

Information about X-DNA, Y-DNA, and mitochondrial DNA can also aid in interpreting chromosome paintings by suggesting which ancestral lines may or may not be the ancestral source of a particular ethnicity admixture assignment. Males inherit X-DNA from their mothers, and females inherit X-DNA from their mothers and paternal grandmothers. If a chromosome painting shows that a unique ethnicity has been assigned to all or a portion of a male’s X-DNA, then the source of that DNA is likely from that individual’s maternal ancestry. If a female test taker’s X-DNA carries segments assigned to a unique ethnicity, it may come from her maternal or paternal grandmother’s ancestry.

Males also inherit a Y chromosome from the father and his direct paternal ancestors. Y-DNA signatures are grouped based on their similarity into “haplogroups,” some of which are geographically or ethnically specific. Suppose you have a high percentage of Northwestern European DNA in your admixture estimate and a Y-DNA haplogroup most commonly found in Western Europe. In that case, it could suggest that at least part of your European admixture originates from your direct paternal ancestors.

All individuals inherit mitochondrial DNA (mtDNA) from their direct maternal ancestors. As with Y-DNA, mtDNA signatures are categorized into haplogroups which can be geographically or ethnically specific. Suppose you have African admixture in your ethnicity estimate and an mtDNA haplogroup commonly found in Africa. In that case, it can suggest that your African admixture originates at least in part from your direct maternal ancestors.

Just because a particular ethnicity admixture assignment appears on the top version of a single chromosome pair and in a different region on the bottom version of the same chromosome pair does not mean that both parents have admixture from that region. In this example from 23andMe, the test taker has Jewish admixture (green) and Sub-Saharan African (shades of pink and purple) admixture in different regions represented on both chromosome copies even though both of these ethnicities are from the test taker's paternal ancestry.

What Next? Pinpointing the Source of Unexpected Autosomal DNA Test Results

While ethnicity admixture estimates and ethnicity chromosome painting can help formulate hypotheses for further investigation, pinpointing the ancestral source(s) of a unique or unexpected admixture assignment most often requires additional consideration of genetic cousins. Identifying genetic cousins who also carry a unique or unexpected ethnicity admixture assignment and then identifying their relationships to each other and to you can help, as can searching for genetic cousins with 100% admixture from a single region and considering their shared matches. At 23andMe, you can download the segment data for the ethnicity chromosome painting and correlate this information with segment data from 23andMe and other companies to identify which genetic cousins share the same ethnicity admixture region and the same segments of DNA.

While not the most critical element of autosomal DNA test results for solving research questions, ethnicity estimates provide an important broad context for genealogical investigation and enable the formation of hypotheses that can be further explored through careful analysis of genetic cousin match lists, documentary evidence, and segment data.

If there are several chromosomes where large overlapping regions on both chromosome copies have been assigned to the same ethnic region, it can indicate that both parents have at least some ancestry from that region. In this example from 23andMe, the test taker has European (blue) and African (pink) admixture on both their paternal and maternal sides as evidenced by large overlapping regions on both chromosome copies.

If you need more help interpreting your Autosomal DNA test results, you can reach out to our team of professional genealogists for more assistance.

februari 16, 2023 by Paul - Legacy Tree Genealogists Researcher 14 Comments

How to Understand Your Closest Autosomal DNA Test Matches

This article is based on a similar article from the January – March 2022 issue of NGS Magazine and is reprinted here with permission. We hope it helps you know how to better understand your autosomal DNA Test matches and what it means for you.

Autosomal DNA test results at the major genetic genealogy testing companies (23andMe, Ancestry, Family Tree DNA, LivingDNA, MyHeritage) include two main elements: ethnicity admixture estimates and genetic cousin match lists. Ethnicity estimates are a central focus of companies' marketing efforts and a significant motivation for many testers (maybe you took a DNA test to find out your ethnicity). They can provide important context for genealogical investigation. However, genetic cousin match lists are the more useful element of autosomal DNA test results for solving family history mysteries and answering long-standing questions about a family tree.

Reviewing the closest genetic cousins in your autosomal DNA test matches list can help confirm the biological accuracy of close proposed genealogical relationships, provide a framework for interpreting more distant genetic relationships and guide future targeted testing efforts. Meanwhile, close genetic relationships to unknown relatives, lower than expected amounts of shared DNA with your known relatives, or a lack of genetic connections to your known tested relatives can signal the possibility of misattributed parentage – a topic we recently discussed here.

How do companies create and prioritize your autosomal DNA test match lists?

Your genetic cousin match lists are created by comparison of your DNA markers against the DNA markers of other customers in a company's database. Autosomal DNA tests analyze several hundred thousand locations (known as SNPs) across each customer's genome. For each location queried, the raw data of the test results report two base-pair values: one maternal and one paternal.

When you and someone else in a company's database share the same marker values on at least one chromosome copy over several hundred consecutive SNPs, it is assumed you share a chunk or segment of DNA. The longer this chunk of DNA, the more likely it is that you and your genetic cousin inherited it from a recent common ancestor. A range of possible or likely relationships is estimated based on the size, position, and number of segments you and your match share.

DNA markers shared segment — The raw data files for these two individuals show that they share at least one of their two markers at each location queried on chromosome 1 over the course of several consecutive markers. This pattern
continues for an additional few thousand markers and represents a shared segment of DNA.

DNA testing companies most often prioritize the order of genetic cousins in their lists based on the total number of centimorgans your genetic cousins share with you. Centimorgans are a measurement unit expressing the likelihood of recombination between two locations on a chromosome over a single generation.

As this likelihood of recombination is dependent on the segment's location on a chromosome and several other factors, there is not a consistent conversion between the length and centimorgan value of a segment. Closer genetic relatives share higher total centimorgan amounts in more clearly defined ranges than more distant genetic relatives.

For example, parents and children will share around 3400 cM (with slight variation depending on the company). Siblings most often share between 2200 and 3020 cM, and if your genetic cousin shares between 2400 cM and 3100 cM, they are almost certainly a full sibling. Half-siblings, aunts, uncles, nieces, and nephews most often share between about 1340 and 2150 cM, and if your genetic cousin shares between 1550 and 1960 cM with you, they are almost certainly related as a half-sibling, aunt, uncle, nephew or niece.

DNA shared cM genetic genealogy — This chart from The Shared cM Project shows the ranges and averages of total shared centimorgans for various relationship levels. The source for this data comes from collaborative data collection from
genealogists who report data regarding known relationships. An interactive version of this chart is available through DNAPainter.com. Image courtesy of Blaine T. Bettinger, thegeneticgenealogist.com,
CC 4.0 Attribution License.

Beyond these relationship levels, ranges of observed and expected amounts of shared DNA overlap more, making the relationship level more ambiguous based on the number of total shared cM between you and your matches. Genetic cousins sharing 600 cM with you might be related as a first cousin, half-first cousin, or first cousin once removed. As the number of shared cMs between you and your genetic cousins decreases, possible relationships increase. While a genetic cousin sharing 600 cM could be related as a first cousin or a first cousin once removed, the number of possibilities is limited to a relationship within four to five generational steps. Meanwhile, a genetic cousin sharing 40 cM could be related anywhere from second to distant cousins.

DNA genealogy testing — Each of the major genetic genealogy testing companies includes a genetic cousin match list as part of their autosomal DNA test results like the ones pictured above from AncestryDNA. As part of initial efforts to analyze and interpret these results, we recommend starting with the closest genetic cousins sharing more than 200 cM. These lists often include a section for each match detailing how much DNA
they share with the test taker.

Each company provides broad relationship category estimates based on the total number of centimorgans you share with particular genetic cousins. Resources for more fine-tuned estimates are available through ”The Shared cM Project” and DNA Painter's ”The Shared cM Project 4.0 tool v4.”

Blaine Bettinger, ”The Shared cM Project,” The Genetic Genealogist (Blog), https://thegeneticgenealogist.com/: accessed November 2021; and,

Jonny Perl, DNA Painter, ”The Shared cM Project 4.0 tool v4,” https://dnapainter.com/tools/sharedcmv4: accessed November 2021; and,

Jonny Perl, DNA Painter, ”The Shared cM Project 4.0 tool v4 beta,” h https://dnapainter.com/tools/sharedcmv4-beta: accessed November 2021.

Evaluation of Closest Genetic Cousins (Over About 200 cM) Using Autosomal DNA Test Matches

If you are beginning to explore your genetic test results, consider starting by analyzing your closest genetic cousins, who share more than 200 centimorgans (about 2.7% at 23andMe). Individuals sharing higher than this amount of DNA are most often related at a level closer than third cousins. Therefore, it is likely that the nature of their relationship to you and your common ancestors' identities can be determined.

DNA centimorgans genetic genealogy — This histogram from the Shared cM project shows the distribution of total amounts of shared DNA between test takers and known aunts, uncles, nieces or nephews. When analyzing total centimorgans shared with known relatives, researchers should consult the relationship probabilities at DNA Painter.
Not only should they determine if the reported total is possible, but they should also consider if the reported total is likely given the proposed relationship, They might also consider whether a half relationship or other relationship is more likely. Image courtesy of Blaine T. Bettinger,
thegeneticgenealogist.com, CC 4.0 Attribution License.

For analysis of closest genetic cousins, consider the following questions:

Do you recognize any of your closest autosomal DNA test matches?

After taking a DNA test, you may be pleasantly surprised to find siblings, aunts, uncles, first cousins, and other close relatives who have already done DNA testing. Even if you do not personally know some of these closest matches, you may find them through a study of attached family trees, collaboration with genetic cousins, or researching the identity of your match and how you are related.

Do your matches have surnames or family trees that clarify their likely relationship?

Even if your match list does not include close recognizable genetic cousins, it might include individuals with surnames from different branches of your family tree, familiar names of distant collateral relatives, or individuals whose family trees aid in the identification of shared ancestors or surnames.

Do your close-known relatives share appropriate amounts of DNA?

Even if your known relatives appear in your match list, there is still more work to do. Do your known relatives or genetic cousins with common ancestors share appropriate amounts of DNA, given their proposed relationships?

Do your first cousins share amounts of DNA appropriate for first cousins, or could they be half-first cousins?

These questions might be answered by utilizing the tools and resources at DNA Painter and the Shared cM Project.

If your known relatives share amounts of DNA more typical of half relationships, you should perform additional research to determine if you, your genetic cousin, or both of you have a case of misattributed parentage somewhere in your ancestral line. You should also explore the possibility that a full relationship is still possible, but the amount of shared DNA is just low or high, given your proposed relationship.

Do you have too many close autosomal DNA test matches?

In some situations, you might have hundreds of close DNA matches sharing more than 200 cM. This can happen if your ancestors lived in an endogamous population where a population's isolation due to language, culture, religion, or geography resulted in many generations of intermarriage. As a result, your genetic cousins may share multiple sets of common ancestors with you, or you may descend from the same common ancestors numerous times. Both scenarios can result in higher amounts of shared DNA than expected, given your closest genealogical relationship to a genetic cousin. Other situations where you might have many matches can occur when your ancestors were members of very large families. In these scenarios, it may be wise to focus on your matches sharing the most DNA and analyzing those relationships first.

Do you have no close matches?

Other times, test takers may not have any close genetic cousins sharing more than 200 cM. Alternatively, they may not have close matches from one of their proposed ancestral lines. If this describes your match list, more information is needed before you jump to a hasty conclusion of misattributed parentage. It may be that your other family members have not yet performed DNA testing either because you descend from a line of small families with few descendants or your ancestors came from a geographic area that is underrepresented in the database. To confirm the biological accuracy of the first few generations of your proposed genealogy, targeted testing or confirmation of previous testing of documented relatives from various ancestral lines may be necessary.

When the close-known relatives in your match list share appropriate amounts of DNA given their proposed relationships, the identities and relationships of these individuals may aid in efforts to interpret and understand the relationships to your more distant genetic cousins through shared match relationships. They might help isolate potentially pertinent genetic cousins from an ancestral line of interest in the context of a specific research question and objective. On the other hand, a lack of close matches raises possibilities for targeted testing of your known relatives.

Alternatively, reviewing your close genetic cousins may result in the discovery of surprise relationships. Perhaps you do not share DNA with close family members known to have tested. Maybe you have no strong genetic connections to cousins from a particular ancestral line. Given proposed relationships with known relatives, you may share less DNA than expected. Maybe you have close genetic cousins who have no known or documented relationship with you. Each of these situations can signal a case of misattributed parentage either for you or your DNA matches. If this is the case, explore this possibility with the guidance of our recent article.

If you have specific questions about your autosomal DNA test match results and would like to have a free consultation with one of our experts, you can fill out our contact form here.

januari 4, 2023 by Paul - Legacy Tree Genealogists Researcher 4 Comments

6 Signs of Misattributed Parentage in Your Genetic Family Tree

While DNA testing and genetic evidence are certainly useful for breaking down challenging historic brick walls, the implications of DNA testing can also hit closer to home in the modern era when it comes to research on misattributed parentage. 

In cases of adoption, unknown parentage or misattributed parentage, genetic genealogy methodologies enable identification of close biological ancestors whose identities might otherwise remain unknown, and which represent immediate brick walls for any genealogist dealing with such a scenario in their immediate family tree.

In this series of blog posts, we explore tips for successful genetic genealogy searches dealing with adoption research, unknown parentage, or misattributed parentage.

(Portions of this article are reprinted with permission from the April-June 2022 issue of NGS Magazine )

Genetic genealogy can (and often does) reveal surprise cases of misattributed parentage in test takers’ family trees. Misattributed parentage or ancestry, where a presumed parent is not the biological parent of an individual or their ancestor, is quite common. Rates of misattributed paternity are estimated to be between 2% and 12% and may vary between populations.1 These rates are based on studies of populations during the 20th and 21st century and may not necessarily be representative of historic rates of misattributed parentage. Even so, exploration of what the low end of this range of rates might mean for an individual's genealogy is informative.

Even with a conservative estimate of 2% probability of a misattributed parentage event per generational linkage, this suggests that approximately 13% of individuals in the general population will have at least one case of misattributed parentage in the first three generations of their family tree (for themselves, a parent, or a grandparent).

Under even more conservative estimates (.5% probability of a misattributed parentage even per generational linkage), most people will have at least one case of misattributed parentage in the first eight generations of their family tree (up to the sixth great grandparent level). Based on this, even if you can document your family tree several generations, it is still a good idea to verify that those documented relationships reflect biological reality using genetic genealogy.

Genetic genealogy test results often provide the initial clues to uncover a misattributed parentage event. These events may even go undetected unless DNA test results are analyzed carefully.

Once a case of misattributed parentage has been detected and confirmed, genetic genealogy can also aid in determining the identity of a biological parent, either for you or one of your ancestors.

Following are some of the telltale signs or clues that you may have a case of misattributed parentage in your family tree, along with some tips of what to do next to determine the identities of biological ancestors.

Clue #1 Unexpected Ethnicity Results

The first clue that you or a close ancestor may have had misattributed parentage could be anomalous ethnicity admixture estimates at one of the major DNA testing companies.

Each company analyzes thousands of DNA markers and determines which combinations of those markers are most likely found in regions around the world. As such they can estimate where some of your recent ancestors lived or came from. Increasingly, companies are not only offering broad ethnicity estimates for larger regions (where ancestors may have lived in the last several hundred to thousand years) but they are also supplementing these reports with specific regions, groups, or migration patterns where a test taker’s ancestors likely lived in the last few hundred years. For more information on how this works, see our article on ethnicity admixture estimates.

Small amounts of ethnicity admixture from populations near to where your ancestors lived are common and even expected, but if you have significant percentages (higher than 5-10%) of ethnicity admixture from unexpected regions and you also have genetic connections to unexpected communities, groups or migration groups, this could suggest misattributed parentage somewhere in your tree.

The size of the unexpected percentage might help you estimate where the misattributed parentage occurred. For example, if your documented family tree is entirely British and you find surprise Jewish admixture, 50% might suggest that you have misattributed parentage, 25% might suggest that one of your parents has misattributed parentage, and 12% might suggest that one of your grandparents has misattributed parentage.

PRO TIP:

Before assuming anomalous ethnicity admixture estimate means misattributed parentage, test at a few major DNA testing companies. Each company maintains its own reference panel, and analytical algorithms for estimating ethnicity. By testing at multiple companies and paying attention to the overarching patterns, it is possible to get a better and more accurate idea of your ethnic origins. If the anomalous result persists across multiple companies, explore the possibility of misattributed ancestry further. Learn how to create your DNA Testing Plan.

Clue #2 Y-DNA Testing Anomalies

Another sign that you might have misattributed parentage at some point in your family tree is if Y-DNA testing uncovers anomalous connections or a lack of connections to expected family members.

When males perform Y-DNA testing at Family Tree DNA, they can sometimes connect with other males who are related along their direct patriline. Sometimes these individuals are close relatives, related within a genealogical timeframe. Other times, these Y-DNA matches are distant relatives whose common ancestors lived before the advent of heritable surnames.

If you take a Y-DNA test and find no Y-DNA matches, it may be that other direct paternal relatives have not yet performed DNA testing.

If you believe other direct paternal relatives have performed DNA testing and you are not matching them, it could indicate that you or they have misattributed parentage somewhere along the direct paternal line.

If you have Y-DNA matches to many individuals with a different shared surname this could mean any of the following:

You could have misattributed parentage on your direct paternal line.
It may be that those relatives are descended from a common ancestor who had misattributed parentage or unknown parentage from direct paternal ancestors with a different surname.
And/or perhaps direct paternal relatives from your distant paternal ancestors have not yet performed DNA testing.

PRO TIP:

If you have Y-DNA test result anomalies, consider target testing known relatives who also descend from your proposed direct paternal ancestors. This can help you pinpoint the generation in which a case of misattributed parentage might have occurred. It can also help you determine if there is a case of misattributed parentage along your direct paternal line or if there might be other explanations for your lack of Y-DNA matches, or unexpected Y-DNA matches.

Clue #3 No shared DNA with close relatives who have also tested

A lack of shared DNA with a close relative who you know (or who you believe) also performed DNA testing can also be a sign of misattributed parentage or ancestry (either for you, or your known relative).

All relatives within the range of second cousins should share at least some DNA with each other. If a known sibling, first cousin, or second cousin has performed DNA testing and is not showing in your match list then ensure that the following are true:

The relative did indeed take and submit the DNA test.
The relative performed DNA testing at the same company where you also tested (companies maintain separate databases, so if a known cousin tests with a different company they will not appear as a match).
The relative has opted into DNA matching (some companies offer the option of performing an autosomal DNA test to obtain ethnicity estimates or other reports, but permit opting out of DNA matching).
The relative’s test results have completed processing (sometimes there is a delay in a cousin showing up in the match lists of others if their test results have just recently completed processing).
The relative is not using an alias or unidentifiable username (sometimes the cousin may be in your match list, but under a username that you do not recognize).

If all the above is true, then there may be a case of misattributed parentage for you or for your known relative. To determine which individual does not descend from the proposed common ancestors, consider the matches in each individual’s genetic test results.

Example Cousin Scenario 1 and 2

Imagine that you took a DNA test along with your paternal first cousin, Sharon. You are both proposed grandchildren of Paul and Helen Smith. When the test results complete processing, you find that you do not share DNA with Sharon. In this situation there are two main possible scenarios. Either you are not a descendant of Paul and Helen Smith (scenario 1), or Sharon is not a descendant of Paul and Helen Smith (scenario 2).

If you share DNA with other descendants or collateral relatives of Paul and Helen Smith, while Sharon does not, you can conclude that Sharon is not a biological descendant of Paul and Helen (scenario 1).
If Sharon shares DNA with descendants or collateral relatives of Paul and Helen which you do not match, then you are not a biological descendant of Paul and Helen (scenario 2).

In this case, it is also possible that neither of you descends from Paul and Helen or that one of you descends from the couple but there are no other tested descendants or collateral relatives. Those scenarios would require additional analysis and exploration.

Scenario 1: You do not share DNA with your proposed paternal first cousin, Sharon (red). You do share DNA with other documented first cousins and collateral relatives of your grandparents at appropriate levels (green) while Sharon does not. In this case, you can conclude that Sharon is not the biological granddaughter of Paul and Helen Smith. Either she is not the biological daughter of Susan, or Susan is not the biological daughter of Paul and Helen Smith.

Note that lack of shared DNA between known relatives strongly indicates a case of misattributed parentage for individuals who are expected to be related within the range of close family to second cousins. More distant relatives in the range of second cousins once removed to more distant relatives may have simply inherited different portions of their shared ancestors’ DNA and may not share DNA with each other.

PRO TIP:

To determine if this is the case for more distant known relatives, determine if you and your matches share DNA with other descendants or collateral relatives of the proposed common ancestors.

Clue #4 Lower than expected amounts of shared DNA with a known relative

Sharing significantly less DNA with a known relative than expected is another sign of possible misattributed parentage. If your known relative shares half the amount of DNA than would be expected given their proposed relationship, it may be that they are a half rather than a full relative.

To evaluate this possibility, utilize the evaluation tools through DNA Painter and the Shared cM Project to evaluate the amount of shared DNA.2

On the one hand, just because a proposed relationship is possible does not necessarily mean that it is likely. If a known relative is sharing a low amount of DNA explore the possibility of a half relationship.

On the other hand, some relatives just happen to share low amounts of DNA, and although there may be a small probability of a proposed relationship, someone must make up the 5% probability for specific relationship levels.

PRO TIP:

To determine if your known relative is a half-relative or to determine if they are just a low sharing full relative, explore the matches shared between you and them to determine if shared cousins include collateral relatives of both of your proposed common ancestors or only one of them.

Example Cousin Scenario 3, 4, 5

Imagine a different situation where you and your first cousin, Sharon, both perform DNA testing at the same testing company. When the results complete processing, you are found to share just 550 centimorgans with each other.

According to DNA Painter’s Shared cM Project 4.0 tool, this amount of shared DNA is much more likely between half first cousins (about 80-90% probability) than it is between full first cousins (about 10-20% probability).

In this situation there are three main possible scenarios:

You are a descendant of Paul and Helen Smith while Sharon is a descendant of only Paul or Helen (scenario 3)
Sharon is a descendant of Paul and Helen Smith while you are a descendant of only Paul or Helen (scenario 4)
Both of you are descendants of Paul and Helen but happen to share a low amount of DNA with each other given your proposed relationship (scenario 5).

If you have genetic cousins who are related through the ancestry of both Paul and Helen, while Sharon only has genetic cousins who are related through Helen and shares consistently low amounts of DNA with other descendants of Paul and Helen then you can conclude Sharon’s parent was not the biological child of Paul but was the child of Helen (scenario 3).

If Sharon has genetic cousins who are related through the ancestry of both Paul and Helen, while you only have genetic cousins who are related through Helen and you share consistently low amounts of DNA with other descendants of Paul and Helen, then you can conclude that your parent was not a biological child of Paul but was the biological child of Helen (scenario 4).

If both you and Sharon have genetic cousins who are related through the ancestry of both Paul and Helen, then you can conclude that you and Sharon are full first cousins but simply share low amounts of DNA given your proposed relationship (scenario 5).

Scenario 4: You share 550 cM of DNA with your paternal first cousin Sharon – an amount of DNA more typical of half first cousin relationships (orange). You share consistently low amounts of DNA with other descendants of Paul and Helen (orange) while Sharon shared appropriate amounts of DNA with the same individuals. Both you and Sharon share DNA with collateral relatives of your grandmother, Helen (green). While Sharon shares DNA with collateral relatives of Paul, you do not (red). In this case, you can conclude that your father, David, was not the biological son of Paul.

Clue #5 Close unknown genetic cousins

Another hallmark of cases of misattributed parentage is the presence of close genetic cousins (those sharing more than 200 cM) for whom no known or documented relationship can be determined in the context of your documented family tree or their documented family tree.

To determine whether you or your match have a case of misattributed parentage in your respective family trees, it is useful in these cases to consider the matches shared between you and the match to determine which family tree those shared matches support.

Example Cousin Scenario 6, 7

Imagine that you have a close genetic cousin, Mary, sharing 600 cM who has an extensive six-generation family tree associated with her test results. Based on the amount of DNA you share with each other; Mary should be related in the range of a first cousin to first cousin once removed.

You could have a case of misattributed parentage in your family tree and may biologically descend from Mary’s ancestors (scenario 6).
Mary could have a case of misattributed parentage in her family tree and could biologically descend from your ancestors (scenario 7).
Alternatively, you could both have cases of misattributed parentage in your trees and may descend from a shared common ancestor that is unknown to either of you (scenario 8).

If your shared matches to Mary are known descendants and collateral relatives of your paternal grandparents, Paul and/or Helen Smith, then we can conclude that Mary is also descended from Paul and/or Helen or one of their collateral relatives and that she has a case of misattributed parentage in her family tree (scenario 6).

Meanwhile, if your shared matches with Mary are all descended from a set of Mary’s second great grandparents, this would indicate that you are also descended from this same couple and that you have a case of misattributed parentage in your family tree (scenario 7).

If all shared matches between you and Mary do not have clear relationships to your respective proposed family trees, but instead form their own cluster of known relatives from a completely different couple, then it may be that both you and Mary have cases of misattributed parentage in your family trees (scenario 8).

Scenario 6: You have a close mystery genetic cousin, Mary, who has an extensive family tree associated with her test results, but no documented shared ancestors (yellow). You share 600 cM of DNA with each other which is typical of a first cousin, or first cousin once removed level of relationship. Mary shares DNA with other descendants and collateral relatives of both Paul and Helen Smith. In this case, you can conclude that Mary is also a descendant of Paul and Helen and has a case of misattributed parentage in recent generations of her family tree.

Clue #6 No genetic connections to a particular branch of your family

One additional clue that can signal a case of misattributed parentage is when your match list lacks representation of collateral relatives through a proposed ancestral line.

However, you should exercise caution in these situations to avoid jumping to a hasty conclusion. In this case, absence of evidence is not necessarily evidence of absence. Just because there are no matches from a particular line does not necessarily mean that you are not biologically descended from that family. Consider the following reasons there may be no genetic connections to a particular branch of your family.

Unrepresented family lines might be composed of several generations of small families that only had one or two children resulting in few living descendants to test in the first place.
Underrepresented families might be composed of recent immigrants from countries, regions and populations which are not well sampled in the database.
In other cases, family members from that line may not have performed DNA testing yet.

In these situations, it is useful to consider the family sizes, geographic origins, and other family details for the ancestral line that is missing in your test results.

If a lack of representation from a particular line accompanies one of the scenarios discussed above (no relationship to a known tested relative, lower than expected amounts of shared DNA with known relatives, or multiple genetic cousins with a documented relationship to each other but not to the test subject), then a case of misattributed parentage is likely.

Even so, the best way to explore the anomaly of missing representation is to target test relatives from that family line in order to test the hypothesis that the lack of matches is due to misattributed parentage at some point along that ancestral line rather than low testing representation from that family in the database.

Imagine that in your case, you have many matches who are related through the ancestry of your maternal grandparents, as well as many matches through the ancestry of your paternal grandmother, but you cannot identify any matches who are related through the ancestry of your paternal grandfather Paul Smith.

If Paul Smith was from a family of ten children and descended from a long line of large families in Colonial America, we might expect there to be at least some matches through this proposed ancestral line. Meanwhile, if Paul was the only child of an only child of an only child and was an immigrant from Germany (where DNA testing is not as prevalent), then the lack of genetic cousins from that ancestral line is more likely due to small family sizes and recent immigration from an underrepresented population in the testing databases.

In either case, targeted testing of a documented relative could help confirm or refute the possibility of a case of misattributed parentage.

What Next?

While none of these signs in isolation or combination are proof of a case of misattributed parentage, if your test results fit one or more of these descriptions, it may be wise to at least consider the possibility of misattributed parentages somewhere in your family tree.

If you come across DNA test results that are anomalous because of ethnicity admixture, Y-DNA anomalies, lack of matching to known relatives, low amounts of shared DNA with known relatives, close genetic relationships to unknown relatives, or a lack of genetic connections to relatives from a particular branch in your family tree, use the tips in this article to pinpoint where a case of misattributed parentage may have occurred and then determine who your biological ancestors were.

If you need help, or even just want someone to review your work to make sure that you are correct in your conclusions, hire a professional genealogist at Legacy Tree to help you explore your biological heritage.

december 19, 2022 by Paul - Legacy Tree Genealogists Researcher 2 Comments

Nine Tips for Successful Adoption Research with Genetic Genealogy

In this series of blog posts, we explore tips for successful genetic genealogy searches dealing with adoption research, unknown parentage, or misattributed parentage.

Approximately 7 million Americans (or 2% of the population) are adopted, and about 140,000 children are adopted each year. Meanwhile, nearly 60% of the U.S. population has had a personal experience with adoption, meaning that they themselves, a family member, or a close friend was adopted, had adopted a child, or had placed a child for adoption.[1] Though the statistics, processes, and documentation may vary, adoption is a common practice in many countries around the world. As a result, many genealogy researchers have recent obstacles in their family trees due to cases of adoption either for themselves or their immediate ancestors.

Genetic genealogy research is an important research avenue for adoptees or their descendants seeking to learn more about their biological ancestry. Even so, researchers should recognize document research avenues that might aid in the effort. Following are nine tips for using documentary and genetic evidence to identify biological parents in a case of recent adoption.

1. Gather as much background information, context, and records as you can to start your adoption research

To successfully identify an adoptee’s biological parents, it is first essential to obtain as much information as possible regarding the context of the adoptee’s conception and birth. This often involves seeking as much documentary evidence as possible.

Interview Those Involved

Individuals involved in the adoption process might be interviewed. The adoptee themselves may have heard information from their adoptive parents. Adoptive parents may be able to share some information regarding the biological parents. If adoptive parents are deceased or are unwilling to share information or if they do not have information to share, there are still some documentary research avenues that might be pursued.

Request Records

Depending on the state, adoptees, and in some cases their immediate family members, may be entitled to original birth certificates, non-identifying information from the adoption agency or the court that handled the adoption, or even the adoption file itself. These records can be immensely helpful for learning information about biological parents and their extended families. Even if non-identifying information was obtained previously, it may be worth requesting again as what is considered non-identifying can be subject to the interpretation of the worker handling the request. Also, an adoptee might consider working with a mutual consent registry to possibly connect with a biological parent. Some states sponsor an official registry, and other organizations maintain some registries.

In some international adoptions, records from the courts or agencies that processed the adoption can sometimes be obtained. Additional documents that might be sought include immigration records, naturalization records, passports, orphanage records, and original civil registration records from the country where an adoptee was born.

Adoption Research Records — Request Records for non-identifying information

Historic Adoption

If researching a historic adoption, keep in mind that confidentiality was not applied to adoption records until about 1920. If an adoption occurred prior to widespread sealed/closed adoption laws, there may be public records relating to an adoption through the court, or newspaper legal notices. Even if records were sealed at a later date, those records are sometimes made available after a certain number of years. In cases where there are still restrictions on access to adoption records and original birth certificates, be sure to consider other sources such as orphanage records, newspaper notices, or agency records which may not be subject to the same restrictions.

Conception Analysis

In addition to the records discussed above, conception analysis is important for establishing context. Full term pregnancies typically range between 247 and 284 days of duration from conception (ovulation) to delivery with 80 percent of pregnancies lasting between 256 and 280 days.[2] Based on this information and bearing in mind the background information recorded in non-identifying information from an adoption file (which sometimes includes duration of the adoptee’s gestation), conception dates can be estimated. Also, remember that an adoptee’s birthplace was not always the same as the place of conception.

2. Be open minded regarding the accuracy of background information

False Information

While it is important to get as much information as you can regarding the context of an adoption, you should also keep in mind that not all information may be correct. Information on original birth certificates may have been falsified. Details from non-identifying information files can be incorrect. Background provided by adoptive parents and others can also be incomplete or false. These differences are sometimes due to intentional efforts to mislead or conceal information on the part of a biological parent, adoptive parent, or other party involved in the adoption process such as cases where a bio-mother attempted to conceal her identity, an agency participated in unethical practices in arranging the adoption, or an adoptive parent is actively discouraging a search.

Inaccurate Information

However, differences between expectations and reality can also be due to simple misunderstandings, miscommunications, or lack of knowledge. Adoptive parents may not be fully aware of the circumstances of an adoptee's birth or may have been told false information about the bio-parents. A biological mother may have misidentified the biological father and provided information about the incorrect individual in interviews with social workers. Even in these cases, if the information is not entirely correct, the background information is still helpful in providing some clues and may include a grain of truth.

Use ”Known” Parents for Research

Sometimes background information can reveal the identity of one or both of an adoptee’s biological parents. In these cases, it is still beneficial to extend the ancestral lines of “known” parents using document evidence to ensure that their family tree aligns with the family trees of genetic cousins. In some cases, a named parent on an original birth certificate or the parent described in an adoption file may not be the biological parent, or information regarding the parent may have been falsified. Extension of the family trees of “known” parents helps researchers detect such scenarios.

3. DNA Test at multiple companies

DNA Test at multiple companies, including 23andMe, Ancestry, FamilyTreeDNA and MyHeritage

Autosomal DNA Testing

When attempting to solve a case of adoption, genetic genealogy testing can help. We recommend starting with autosomal DNA testing at each of the major DNA testing companies: 23andMe, Ancestry, FamilyTreeDNA, and MyHeritage (note that MyHeritage and FamilyTreeDNA accept transfers of raw data from other testing companies). Raw data might also be transferred to GEDmatch, Geneanet and other companies that accept transfers of data. Each company maintains separate databases of tested customers and it is never known where the closest and most important genetic cousins might have tested. Other types of DNA can also be helpful for adoption searches.

X-DNA Testing

X-DNA (which is tested as part of autosomal DNA tests) can sometimes help narrow the search for common ancestors between an adoptee and a genetic cousin. 23andMe, FamilyTreeDNA and GEDmatch all report on shared X-DNA between matches.

Y-DNA Testing

For male adoptees, or direct paternal descendants of male adoptees, Y-DNA can be helpful for identifying potential surnames or direct paternal origins for a biological father (Y-DNA is inherited along the direct paternal line – the same inheritance pattern as surnames in some countries). FamilyTreeDNA offers Y-DNA testing and 23andMe reports on broad Y-DNA haplogroup categories which can sometimes be used for evaluating relationship scenarios to close genetic cousins.

Mitochondrial DNA Testing

For male and female adoptees, or for direct maternal descendants of female adoptees, mitochondrial DNA testing can sometimes aid in learning about a biological mother or direct maternal origins. FamilyTreeDNA offers mitochondrial DNA testing and 23andMe reports on broad mtDNA haplogroup categories which can sometimes be used for evaluating relationship scenarios to close genetic cousins.

4. DNA Target test others

In addition to testing yourself or the adoptee, it might be beneficial to test others to aid in your genetic genealogy search. If a test taker is the adoptee themselves, then it can sometimes feel like there are no targeted testing options. However, adoptees might consider working with genetic cousins to target test their older relatives in order to pinpoint the nature of a relationship. For example, if an adoptee has a close genetic cousin who does not yet have any other tested close relatives, they might work together to target test aunts, uncles, parents, cousins, and other relatives of the genetic match to determine which branch of the match’s family tree is the source of share DNA with the adoptee.

Often through genetic genealogy analysis, adoptees can narrow a list of bio-parent candidates down to a handful of individuals. To further determine the identity of a bio-parent, it may be necessary to target test living descendants or other close living relatives of those individuals.

5. Try to distinguish paternal vs. maternal relatives

In adoption cases, genetic genealogy analysis can quickly become overwhelming because adoptees are often searching for two unknowns: a biological father and a biological mother. As a result, all genetic cousins are potentially pertinent to the search and if there are a large number of them, then the search can quickly become overwhelming.

Sorting DNA matches based on their relationships to each other is a great approach for any genetic genealogy case, but it is particularly important in adoption cases. At the most basic level, efforts should be made to try and distinguish relatives of one parent from relatives of another.

If an adoptees parents have different ethnic origins, ethnicity estimates can sometimes help in this process. Y-DNA, mtDNA, and X-DNA evidence can also aid in this effort. AncestryDNA recently began separating match lists into parent 1 and parent 2 categories.

Other companies which provide segment data regarding genetic cousins (23andme, FamilyTreeDNA, MyHeritage and GEDmatch) can also be used to identify genetic cousins who are sharing DNA in the same chromosomal regions but on different sides of a test taker’s family tree. Organizing genetic matches in this way can make the search more straightforward and feasible.

6. Collaborate with genetic cousins

As mentioned previously, in adoption searches, collaborating with close genetic cousins can be an important targeted testing opportunity. Even beyond these benefits, collaborating with genetic cousins can save time in researching and extending family trees for key genetic matches. They may be aware of bio-parent candidates in their extended family. They may be able to provide information to help extend their family tree enabling identification of common ancestors with shared matches and identification of ancestral candidates. Further, by building a relationship with these genetic cousins, you may be able to gain an ally in your search. Communication with bio-parent candidates from within their own family may be more successful than cold-call attempts from outside their family.

It can be nerve-wracking to contact close genetic cousins and bio-family. For more recommendations on establishing contact, see our blog post on how to contact your birth parent or sibling or this blog post on how to get responses from your DNA matches

7. Be patient with yourself, your matches, and others in your collaboration efforts

As important as it may be to establish contact with close genetic cousins and bio-family, these efforts can certainly be emotional and stressful. We recommend taking it slow so that you, your bio-family, and your genetic cousins have sufficient time to process new information that can be life-changing. Keep in mind that you may have had several months or even years to process knowledge of your adoption, while it may be the first time that some of the people you are contacting have heard or learned about your experience and existence. For you and for them, consider some of these resources for DNA surprises in a family tree.

If you don’t receive immediate responses from the individuals you have contacted, give them some time before following up. Don’t assume that no response is a rejection. Particularly for genetic cousins, they may not have received or seen your communication through the company messaging system. You may have attempted contact through an outdated address, phone number or email. They may not regularly check their social media accounts. Alternatively, they may just need time to process the new information and decide how they are going to move forward.

8. Use DNA and documents in adoption research to find the right people in the right place at the right time

Once common ancestors and relationships are identified for clusters of genetic cousins, then researchers can begin the process of searching for connections between ancestral candidates and finding individuals who were in the right place at the right time to be the source of shared DNA with DNA matches.

In adoption research, be sure to focus on the conception date and context rather than the birthdate and birthplace as the two are often different. In some adoption cases, it may be possible to narrow down a pool of candidates to a set of siblings on one side and a set of siblings on the other side. It may even be possible to narrow down further based on Y-DNA, mtDNA and X-DNA. Even so, there may still be several candidates.

If targeted testing and collaboration efforts are unfruitful or impossible, consider narrowing a pool of candidates down further by comparing what is known about a family against non-ID information or other background context. Also try narrowing a pool of candidates based on geographic proximity and life situation at the time of context. For some ideas on how to do this, review our blog on finding the right people at the right place at the right time. While it may not always be possible to prove the identity of a biological parent with DNA, it may be possible to use document evidence to identify the most likely candidate from a particular family.

9. Have a professional genealogist review your adoption research work

Searching for biological parents in an adoption research case can be a stressful and emotional journey in self-discovery. Contacting bio-relatives can be nerve-wracking. Results of contact with bio-family can be joyous or heart-breaking. Because of these considerations you will want to make sure that you are as confident as possible in your conclusions in a bio-parent search before contacting bio-parents, siblings, or other relatives.

Our project packages offer an excellent opportunity for a professional researcher to review previous work you may have performed and identify other scenarios you may not have considered. Even if you have arrived at a valid conclusion, you will want to make sure that your reasoning is written in a clear and well communicated manner to put newfound family members at ease in their questions and concerns. Our experienced and professional genealogists at Legacy Tree have found that bio-families of an adoptee are often extremely interested in reviewing our reports to better understand how they were identified as close biological family of a client. By working with a professional researcher, you can move forward in contact with confidence, and you can make sure that you have correct and proven answers in the important search to identify your biological parents.

For assistance with your adoption research, or to verify the information you have found, contact the experts at Legacy Tree Genealogists.

[1] Adoption Network, “U.S. Adoption Statistics,” https://adoptionnetwork.com/adoption-myths-facts/domestic-us-statistics/, accessed August 2021.

[2] A.M. Jucik et al, “Length of Human Pregnancy and contributors to its natural variation,” Human Reproduction (Oxford, England), 2013 Oct; 28(10): 2848–2855, http://www.ncbi.nlm.nih.gov, accessed December 2022.

oktober 17, 2022 by Paul - Legacy Tree Genealogists Researcher 8 Comments

Five Ways to Use the New DNA Coverage Estimator Tool at DNA Painter

The DNA Coverage Estimator is now available and makes the process of identifying matching ancestors through DNA much simpler than ever before.

In April 2018, Legacy Tree Genealogists published an article by Paul Woodbury introducing the concept of DNA coverage – the amount of an ancestor’s DNA represented in a DNA database through the test results of their tested descendants. Different descendants of an ancestor inherit different portions of that individual’s DNA. Therefore, they have different shared segments and total amounts of shared DNA with key genetic cousins. They may even have altogether unique key genetic cousins not shared with other descendants of the target ancestor. By testing multiple descendants of a research subject, it is possible to maximize the coverage of that individual’s DNA in a database.

As part of our previous article, we presented several equations to help in calculating and estimating the coverage of an ancestor. Coverage estimates can be helpful for prioritizing DNA testing candidates, developing strategies for collaboration with existing genetic cousins, and estimating amounts of DNA an ancestor might have shared with a key match or group of matches. However, using the published equations has often been cumbersome and complicated. Further the set up of the equations has limited the scalability for calculating coverage estimates for descendants of large families.

Recently, Leah Larkin at the DNA Geek refined and simplified the original equations to a more intuitive approach (See her description of the math here). Using these revised equations, Leah and Paul worked with Jonny Perl (owner and developer of DNA Painter) to create the coverage estimator tool. (To learn more about the tool and how to use it, visit Jonny’s article at DNA Painter).

This tool makes coverage analysis much more straightforward and accessible for genealogists -no more complicated calculations or limitations on the number of descendants to include. Here are just a few ideas of how you might use the coverage estimator tool in your research.

1. Estimate Your Ancestor’s Coverage in a Single Testing Database

One way you might use the coverage estimator tool is by entering all of the tested descendants of a known ancestor at a single DNA testing company (no mixing and matching between databases) in order to estimate their coverage at that company. If you have used WATO previously, you might use the same tree structure and mark the individuals who have tested.

For example, in the attached screenshot, I have identified the five tested descendants of Susan at AncestryDNA. Their combined DNA tests account for approximately 78.9% of Susan’s DNA at that company.

Keep in mind that while including all of the tested descendants of a research subject at a particular DNA testing company can give you an idea of what the coverage of that ancestor is in that particular database, the only way to take full advantage of that coverage is to collaborate with and seek access to the test results of the other tested descendants.

Without access to DNA test results for other descendants, you will still be limited to the coverage created by your own DNA test results. You won’t be able to learn about the additional chunks of DNA that other descendants inherited (and by extension the amounts of DNA shared with key genetic cousins) or even the additional key genetic cousins that you don’t match but they do.

2. Prioritize the Genetic Cousins with Whom You Should Collaborate

Because you can only fully leverage the coverage of your ancestor’s DNA by obtaining access to the test results of other descendants, another way you might use the coverage tool is to take the tree you created for your ancestor’s tested descendants and unmark all individuals for whom you do not currently have test result access keeping only those for whom you do have access. This will estimate how much of your ancestor’s DNA you have access to through tested descendants (we could call it your active coverage).

The DNA Painter tool will identify which individual should be the next tester to maximize your active coverage. (In this case, these individuals are already tested, but this information might be interpreted to help you understand who you should reach out to and seek to collaborate with). If possible, you should try to work with those individuals to obtain access to their test results and thereby benefit from the additional perspective, segments, matches, and relationships that their test results can provide for the purposes of your research.

The tool will also reveal how much more helpful these individuals could be for increasing your coverage. If you attempt to collaborate with the highest priority individual and they decline to share test result access, you can mark them as “unwilling to test” in the data, and the tool will let you know who is the next best priority for collaboration.

In the same example from above, I have access to the test results of Elizabeth, Peter and Bernard, but not Matthew or Lillian, so I unmarked Matthew and Lillian as having tested. This reveals that my active coverage (the coverage based on the test results I actually have access to) is about 68.8%. The tool then tells me that the next best person to test (or in this case, the best person for me to work with for collaboration) would be Lillian. Getting access to her test results would increase my active coverage by 7.8%.

3. Prioritize the Relatives You Should Invite to Test or Transfer

To this point we have only considered already-tested descendants of a research subject ancestor, but the Coverage Estimator tool can also help you identify priorities for targeted testing or autosomal DNA transfers.

Consider adding other known descendants of your research subject to your chart. These individuals might not have performed DNA testing yet. On the other hand, they may have performed DNA testing, but at a different database.

When you add these people into your tree, the tool will identify who you should contact to invite to perform DNA testing (or to upload their test results from elsewhere) in order to maximize coverage. As in the case of collaboration prioritization described above, if individuals decline to test or transfer, you can mark them as “unwilling to test” and the tool will identify the next best candidates.

Alternatively, if they indicate that they are willing (but they haven’t done it yet, or you will need to wait for the results to process) you can mark that they are willing to test, and the tool will update to identify the next best testing or transfer option for you to consider.

There will be a decreasing return on investment as you test more relatives. As potential increases in coverage become smaller and smaller with each new testing candidate that agrees to test or transfer (or who declines), you might want to consider if the potential increase in coverage is worth it for your case.

Keep in mind that 1% of an individual’s DNA represents about 70 centimorgans of DNA. Is 70 centimorgans more coverage worth the cost of a test? You decide.

In our example case, imagine that Susan had another son, John, who has two living sons. When we add them to the tree, the tool will identify them as the next best testing candidates to invite to test.

4. Estimate the Amount of DNA Your Ancestor Shared with a Genetic Cousin

Once you have started to collaborate with living descendants of a research subject and have obtained access to their test results, arranged transfers of their results into a desired database or arranged targeted testing, you can take coverage analysis a step further to being reconstructing the DNA of your research subject ancestor and estimating how much DNA they might have shared with key genetic cousins.

Consider a scenario where you and several other descendants of your research subject are all sharing DNA with a key genetic cousin who might be related through the ancestor of your subject. If you are working with results at a company that reports on segment data, you might generate a comparison between the key match and all independent tested descendants of your research subject. Next, you can determine the total number of centimorgans that match shares on unique segments with all of the descendants of the research subject. S

Some tools that might help with this include:

>DNA Painter’s Centimorgan Estimator tool (take the start position of one segment and the end position of a partially overlapping segment and calculate the length of the composite segment)

>DNA Painter’s Distinct Segment Generator (copy and paste two or more segments that multiple family members share with a single match and get the cM values for each composite segment and the total shared cM).

Once you know how much DNA a match shares with all of the tested descendants of the research subject, divide the total number by the coverage estimate as a decimal (e.g. 70.1% = .701) and you can estimate how much DNA your research subject might have shared with the genetic cousin. From there, you can evaluate the likely relationship levels using DNA Painter’s Shared cM Project tool.

Estimates are…Estimates

Keep in mind that the estimates provided by the Coverage Estimator are just that – ESTIMATES. The true coverage of an ancestor may be lower or higher given that genetic inheritance is random. As such, you should be careful in making assumptions and conclusions based off of this data.

As a general rule, the closer relatives a research subject has and the more tested descendants they have from unique descent lines, the closer the coverage estimate will be to the true coverage of the subject. At the very least (assuming there are not multiple relationships between the descendants of the subject and the key match), engaging in analysis of unique shared segments can reveal the minimum amount of DNA that an ancestor would have shared with a key genetic cousin.

In our example case, I was able to get the test results of Elizabeth, Peter and Bernie transferred to GEDmatch.com. I also managed to collaborate with a key genetic cousin, Katy, and invite that individual to transfer their test results to GEDmatch. While Elizabeth was born in the 1930s, and Peter and Bernie were born in the 1960s, Katy was born in the 1990s (and may be a generation further removed from the common ancestors with Susan’s descendants).

Comparisons of Katy’s DNA against Elizabeth, Peter and Bernie reveals that she shares 351 cM of DNA on unique segments with Susan’s tested descendants. Assuming that all of this shared DNA came from a common ancestor between Katy and Susan, we can conclude that Susan and Katy would have shared at least 351 cM of DNA with each other.

However, the combined results of Elizabeth, Peter and Bernie only account for a portion of Susan’s DNA – about 68.8% of her DNA according to the Coverage Estimator tool. If we assume that the 351 cM of DNA that Katy shares with Susan’s descendants represents only 68.8% of the DNA she would have shared with Susan, we estimate that Katy might have shared approximately 510 cM.

With that level of sharing, we would expect that Katy is related to Susan at the level of a first cousin once removed or (given her age) possibly at the genetically equivalent level of a great-grandniece. For more information on navigating genetically equivalent relationships see our article on the subject.

The amounts of DNA that Katy shares with Elizabeth, Peter and Bernie separately corroborates this hypothesis, but the combined unique segments and application of coverage estimates provides stronger evidence of the proposed relationship at higher probabilities than any of the amounts of shared DNA between Katy and Elizabeth, Katy and Peter or Katy and Bernie.

5. Estimate the Amount of DNA Your Ancestor Shared with a Deceased Relative

In the case above, we considered a scenario where a group of descendants of a research subject were compared against a single genetic match. To take it one step further, you might also consider the unique shared segments between two groups of matches. You could calculate the coverage of the descendants of the research subject for whom you have test result access, and then in a new chart, calculate the estimated coverage of a candidate relative based on the relationships between the tested descendants of the candidate.

Use the same tools as were utilized in the previous recommendation (DNA Painter’s Centimorgan Estimator, and Distinct Segment Generator) to determine the segments that the research subject’s descendants share with the candidate relative’s descendants. Alternatively, you can get all individuals transferred to GEDmatch and use the Lazarus tool to identify the segments shared between both groups.

Next, divide by the coverage of the research subject (in decimal format) and divide again by the coverage of the relative candidate (in decimal format). In this way you can estimate how much DNA the research subject and the relative candidate would have shared in common with each other.

In our sample case, after transferring the test results of Elizabeth, Peter and Bernie to GEDmatch, we found a group of additional genetic cousins already at GEDmatch including a pair of siblings and their aunt (coverage of 68.8% for the common ancestor). All three matches descended from a woman named Laverna. Using the Lazarus tool with Elizabeth, Peter and Bernie in one group and these three matches in the other group, we found that Susan’s descendants shared 472.2 cM of DNA with the three descendants of Laverna. When we divided this by .688 (for Susan’s coverage) and by .688 (for Laverna’s coverage) we found that Susan and Laverna might have shared approximately 999 cM of DNA (100% probability of a first cousin or genetically equivalent relationship). Additional exploration revealed that Laverna was a great-niece of Susan (which is genetically equivalent to a first cousin relationship).

Again, keep in mind that these are estimates, the closer the descendants of each individual, the more independent descendants who have tested, and the higher the estimated coverage, the more accurate the estimates of how much DNA a research subject may have shared with a match or with another relative candidate.

Give it a try, use the Coverage Estimator tool to estimate the coverage of an ancestor’s DNA in any given testing database, to prioritize the individuals with whom you will collaborate, seek access to test results, invite to transfer or invite to test, and ultimately to help determine the amount of DNA your ancestor shared with a deceased relative.

If you have a tough DNA mystery you'd like to solve, our DNA experts can help! Contact us today for a free consultation to discuss which of our project options works best for you.

juni 15, 2022 by Paul - Legacy Tree Genealogists Researcher Leave a Comment

Introduction to Ethnicity Admixture

Paul Woodbury is a DNA team lead and professional researcher at Legacy Tree Genealogists where he has helped to solve hundreds of genetic genealogy cases. In this article, a reprint from an issue of NGS Magazine, Paul discusses how genetic ethnicity estimates can provide valuable clues for the composition of a test taker’s family tree. This article is published with permission.

Obtaining autosomal ethnicity admixture results is the primary reason many people perform DNA testing. The DNA testing companies recognize this interest and in recent years have made genetic ethnicity admixture estimates the focus of their marketing efforts.

In fact, autosomal DNA test results from the major companies include at least two elements: ethnicity admixture estimates and genetic cousin match lists. While the match lists are typically the most useful elements for genealogical research, ethnicity admixture estimates can provide significant context and clues regarding a test taker’s family tree.

What is ethnicity?

An ethnicity is a grouping of people who identify with each other based on shared attributes that distinguish them from other groups, such as traditions, ancestry, language, culture, history, or religion. Individuals of the same ethnicity often belong to the same population (all humans living in a geographic area), and in turn, may share a similar gene pool.

First, it is worth noting that test takers inherit DNA from people rather than places. While some are accustomed to describing their ethnicity admixture in terms of where their DNA came from, people actually inherit DNA from ancestors who lived in populations residing in specific locations rather than from the place where their ancestors lived.

This is an important distinction due to the long history of human migration. While an individual’s more recent ancestors may have lived in the same location for hundreds of years, earlier generations may have come from different and perhaps geographically distant populations—which might result in surprising ethnicity estimates based on genetic information.

Map of France showing Brittany, Alsace, and the Basque country, areas with distinct linguistic and cultural histories underscored by genetic differences in France as a whole. Modern boundaries of countries do not always align with the boundaries of historic populations. Eric Gaba, “France location map-Departements-2015,” Wikimedia Commons (https://commons.wikimedia.org), CC Attribution-Share Alike 4.0 International license; labels added by author. — Map of France showing Brittany, Alsace, and the Basque country, areas with distinct linguistic and cultural histories underscored by genetic differences in France as a whole. Modern boundaries do not always align with the boundaries of historic populations. Eric Gaba, “France location map-Departements-2015,” Wikimedia Commons (https://commons.wikimedia.org), CC Attribution-Share Alike 4.0 International license; labels added by author.

Ancestors of a test subject were members of the wider populations in which they lived. Some populations have been isolated from surrounding populations for hundreds to thousands of years due to language, geography, religion, or other factors.

When a population is isolated, the mutations and unique genetic markers generated and commonly held within the population differentiate it genetically from other populations. Other populations have had frequent interaction, migration, and gene flow with surrounding populations, making it difficult to determine which DNA corresponds to historical populations.

While genetic ethnicity estimates would ideally rely on historical DNA samples of individuals who were members of a population, limitations on historical DNA samples require inference of ethnicity based on current populations. However, the boundaries of modern states do not always align well with historically distinct populations.

For example, what is “French” DNA? Is it the DNA of the population of Brittany, which has strong historical connections to the Celtic populations of the British Isles? Is French DNA the DNA of the population of Alsace and Lorraine in eastern France, which has switched between French and German jurisdictions several times over the last several hundred years? Is French DNA the DNA of the Basques on the southern French border, who have been isolated by language and geography for thousands of years? Is French DNA the DNA of people who have lived for generations in and around Paris?

To answer such questions and provide ethnicity estimates, each genetic genealogy testing company relies on some basic principles.

How it works

While each company uses different approaches to provide ethnicity estimates, these methods share some of the same elements: curation of reference panels, the definition of populations, and probability assignment.

In order to determine ethnicity admixture and estimate the populations to which a test taker’s ancestors belonged in the past, the companies first identify individuals whose ancestors all lived in the same region. The companies use extant public databases as well as samples from their own databases to curate a reference panel of samples for individuals whose ancestry is from a single population.

In this effort, they seek unrelated individuals who do not share large segments or chunks of DNA with each other due to recent common ancestry. They also apply quality control measures such as principal component analysis (PCA) to remove outliers: individuals whose genetic ancestry does not coincide with their reported genealogical ancestry or whose genetic profiles are extremely dissimilar to other individuals from the same tested population. Through this process, DNA testing companies can identify markers of DNA that are only found or are predominantly found, in a single population or in a handful of closely associated populations.

Based on sampling methods, residences of test takers and their ancestors, and genetic similarity between the samples in a population, the companies define regions or populations with unique and distinct genetic profiles.

Danish admixture example — Each company defines populations and regions differently. At AncestryDNA, Danish admixture is sometimes split between Norway, Sweden, and Germanic Europe regions, while at Family Tree DNA, Denmark is included in both the Scandinavia and Central Europe designations.

Because companies use different reference panels, they define these regions differently, too. For example, an individual with several generations of ancestry in Denmark may be assigned Scandinavian ancestry by one company, Norwegian and Swedish ancestry by another company, and Germanic ancestry by another company, due to the ways regional boundaries are drawn and defined by the different companies.

While each company is typically able to distinguish between drastically different and geographically distant populations, some may not be able to distinguish as well between geographically adjacent or historically linked populations.

Currently, AncestryDNA’s reference panel has 45,000 samples, 23andMe has 14,000, and MyHeritage has 5,000.[1] Other companies have not reported the size of their reference panels, but they are probably smaller.[2] As more people from a population are tested and included in a reference panel, a more fine-tuned definition of populations becomes possible. Therefore, it is likely that as companies expand their reference panels to include more samples from individual populations, their ethnicity estimates will continually be refined into smaller populations.

*“DNA Story for Private,” Ethnicity Estimate, updated, private database, Ancestry (https://ancestry.com)*
*“myOrigins,” ethnic makeup percentage for kit private, private database, FamilyTreeDNA (https://familytreedna.com)*

Once a company has assembled a reference panel, it applies different algorithms and approaches to analyze a test taker’s data. Each testing company tests several hundred thousand markers of DNA across a tester’s genome called single nucleotide polymorphisms (SNPs), which are hotspots for genetic variability in human populations. Testing companies analyze a portion of these SNPs as part of ethnicity admixture estimation and consider the prevalence of particular SNPs in specific populations.

Ancestry and 23andMe chop a test taker’s DNA results into smaller chunks or windows of consecutive markers, compare each window to the reference panel and assign the chunk to the population in which its genetic profile is most likely to occur. These chunks and their corresponding assignments are then used to provide percentage estimates of ethnicity regions.

Genetic Communities, Recent Ancestor Locations, and Genetic Groups

Each testing company’s ethnicity estimates report percentages of DNA assigned to populations or regions where a test taker’s ancestors may have lived within the last thousand years. In addition, AncestryDNA, 23andMe, and MyHeritage have started supplementing these estimates with reports of locations and countries where a test taker’s ancestors may have lived more recently and migration patterns in which ancestors may have participated in the last few hundred years.

While broad ethnicity admixture estimates provide high-level context for an individual’s ancestry, these communities, groups, and locations can provide specific clues and hints for follow-up in a genealogical investigation.

Ethnicity estimates consider the prevalence of specific SNP markers in a population and assign percentages of ethnicity, based on similarity to a reference panel. The estimates might be anomalous or unrepresentative of expected ethnicity regions due to historical migrations or population characteristics.

Particular communities, locations, and groups are assigned based on networks of individuals who share large chunks of DNA from recent common ancestors as well as recent ancestral locations, communities, or migration patterns. These communities, locations, and groups are often much more accurate and representative of recent ancestral heritage, although percentages are not assigned to them.

A test taker’s assignment to an unexpected community, location, or group could be due to recent misattributed ancestry or a migration pattern associated with a particular area. A tester from Denmark may have connections to descendants of Danish immigrants to the United States, or a tester from Ghana may find connections to communities of descendants of enslaved communities in the Caribbean.

Why the differences?

Some individuals who test at multiple DNA testing companies receive different ethnicity estimates from them. These differences and changes are not a reflection of the validity of the underlying science, but rather the differences between the reference populations, algorithms, and approaches used by each of the companies.

Even if users test at a single company, it is likely that over the course of several years they will receive updates to their ethnicity admixture estimates. These updates inevitably cause some to complain of their “lost” ethnicities or decreases in their percentages.

Conclusion

In the end, ethnicity estimates are still estimates. As reference panels grow larger, and as companies refine their methods and algorithms for estimation, ethnicity estimates will continue to become more accurate and representative. Even so, ethnicity estimates as they currently stand can provide valuable context and clues for the structure and composition of a test taker’s family tree.

Legacy Tree Genealogists has been at the forefront of genetic genealogy research services for almost two decades. Our team of experts has solved DNA-related cases and can help you solve your family DNA puzzles! Contact us today for a free quote.

Sources

Catherine A. Ball, et al., “Ethnicity Estimate 2020 White Paper,” Ancestry (https://www.ancestrycdn.com/dna/static/pdf/whitepapers/Ethnicity2020_ white_paperV2.pdf). Eric Y. Durand, et al., “A scalable pipeline for local ancestry inference using tens of thousands of reference haplotypes,” updated 7 December 2020, 23andMe (https://permalinks.23andme.com/pdf/23-16_ancestry_composition.pdf). Esther, “Introducing our New DNA Ethnicity Analysis,” MyHeritage, 1 June 2017 (https://blog.myheritage.com/2017/06/introducing-our-new-dna-ethnicity-analysis).
Jayne Ekins, “DNA Ethnicity Estimation: Reference Panels,” Your DNA Guide (https://www.yourdnaguide.com/ydgblog/2019/6/6/dna-ethnicity-estimation-reference-panels).