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Eight Steps to Pursue with New Autosomal DNA Test Results

DNA Test ResultsPaul 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 steps a researcher could take to begin using DNA test results. This article is published with permission.

Several weeks after the submission of a DNA sample, the results finally arrive! An email appears announcing that the test has completed processing. It includes a link to sign in to review the test results. But what comes next? Where to start? The following are my recommendations for the first steps a researcher might take to begin using test results. This article provides a brief overview, and future columns will dig deeper into each of these topics.

Ethnicity Estimates
Ethnicity estimates often identify the regions where a test taker’s ancestors lived in the last thousand years and more specific genetic communities associated with the ancestors in recent centuries. Courtesy of Ancestry.

  1. Set up a profile and attach a family tree

First, if a profile has not been created, set one up. When considering what to include, review my previous article on this topic. [1] 

Adding a profile image, answering questions regarding research interests, listing ancestral surnames, and attaching a family tree to the account can make DNA test results more useful. These items also help make test takers more approachable from the perspective of their newfound genetic cousins.  

  1. Review ethnicity admixture reports

Ethnicity admixture is one of the major reasons that people initially pursue DNA testing. Each of the testing companies invests attention, advertising, and marketing for this element. While these reports are typically not very helpful for genealogical research questions, they do provide a broad context for other genetic genealogy pursuits. They also provide a good introduction to DNA test results.  

Often these results include ethnicity admixture regions indicating the broad geographic areas where a test taker’s ancestors may have lived within the last thousand years as well as more specific genetic communities or ancestral populations that may have been associated with the ancestors in recent centuries.  

When evaluating ethnicity admixture reports, researchers might ask these questions:

▪ Does the test taker have significantly more than 50 percent admixture from a particular region? If so, both parents may have ancestry from that region since individuals inherit only 50 percent of their autosomal DNA from each parent.  

▪ Does the test taker have an even split between two main ethnic regions? If so, one parent may be from one area and the other parent from the other.  

▪ Given the documented family tree of the test taker, do the ethnicity results generally align with expectations? Keep in mind that some populations were historically admixed, so it is possible that admixture from an expected region has been assigned to a neighboring region or otherwise associated region.  

▪ Are any admixture regions or results anomalous, given the context of the test taker’s family tree? Anomalous in this context means admixture that is 10 percent higher or lower than would be expected from particular regions and their neighbors. 

▪ Do any genetic communities or more specific highlighted ancestral regions fit with what is known regarding the individual’s family tree?  

If surprises occur in a test taker’s results, I recommend exploring the anomalies further before jumping to a hasty conclusion. Consider whether unexpected admixture regions might be associated with a known branch of the test taker’s family tree. Explore how the testing company organizes and categorizes specific regions and what ethnic admixture might be expected for individuals from those regions. If an aspect of test results still does not make sense, consider shared matches. 

This chart demonstrates that close relationships have clearly defined ranges of amounts of shared DNA, while more distant relationships have more overlap in amounts of shared DNA. Blaine Bettinger, “The Shared cM Project – Version 4.0,” The Genetic Genealogist blog, https://thegeneticgenealogist.com. CC 4.0 Attribution License.

  1. Review the closest genetic cousins

Perhaps the most genealogically useful part of a user’s DNA test results is the list of genetic cousins. Each company presents a list of individuals who are likely related to the test taker based on shared DNA. Shared DNA is measured in centimorgans (cMs), a measure of the likelihood of recombination as well as the number of segments individuals share with each other. The more total centimorgans a test taker and a genetic cousin share, the more likely that they share recent common ancestors.  

Some ranges of shared cMs are much more likely for particular relationship levels than they are for others. For example, the amounts of DNA shared between siblings are much larger than the amounts of DNA shared between first cousins. However, with more distant relationships, distinguishing between relationship levels can be more difficult. A third cousin could share as much DNA with a test subject as a fourth cousin, and a fifth cousin could share as much DNA as an eighth cousin.  

Each testing company organizes DNA match lists by default based on amounts of shared DNA, with the closest likely relatives listed first. The closest matches in a test taker’s list of genetic cousins are those for whom it is most likely possible to determine the nature of a relationship. Clicking through to view their profiles may give insight into their family trees.  

When reviewing the match list of a test taker, researchers might consider these questions:  

▪ Have any close relatives of the test taker performed DNA testing? Do they appear in the match list as would be expected?  

▪ Do any known relatives share amounts of DNA consistent with their proposed relationships? Keep in mind that half-relatives share half the amount of DNA that would be expected for a  full relationship. To evaluate amounts of shared DNA, review the Shared cM Project Calculator at DNA Painter. [2]  

▪ Are there any close genetic cousins (sharing more than 200 cM) who are unknown? Do they have family trees that help reveal their likely relationship?  

If close tested relatives do not appear in a match list or share less DNA than would be expected, or if unknown close matches appear, consider the possibility of misattributed parentage for either the test subject or the relative. Follow the next steps to aid in determining how they might be related.  

  1. Consider shared matches

Interpretation of autosomal DNA test results is established on the principle that when two individuals share DNA with each other, they share a common ancestor. When those two individuals also share matches in common, those shared (or in-common-with) matches are often related through the same ancestral lines. 

Analysis of these clusters of shared matches can help researchers categorize groups of matches with specific lines of ancestry and quickly determine how an unknown relative might be related to a test taker.

Identification of these groups can also aid in organizing and filtering a match list to isolate genetic cousins who may be related through a line of interest and whose relationships, in turn, may be pertinent to answering a genealogical research question. This approach for considering shared matches is most effective in non-endogamous populations, where it is most likely that individuals share only a single relationship. [3]

Smart Art Relationship Chart
Microsoft Office products include a SmartArt feature in a hierarchy format which researchers can utilize to create relationship charts between genetic cousins.

  1. Contact genetic cousins

Once a researcher has determined the likely relationship for an unknown relative or at least determined through which branch of a test subject’s family they are likely related to, it can be beneficial to contact that person to request additional information regarding his or her family tree. When a genetic cousin’s relationship is difficult to determine, collaboration between two individuals can help in the successful determination of the connection.  

Each DNA testing company offers avenues for contact with genetic cousins which can aid in establishing relationships of collaboration and cooperation to solve genealogical problems. Even for those genetic cousins whose relationship is known, it may be helpful to establish contact to learn about records, photographs, stories, and information passed down to them through their family or obtained through another person’s family history research efforts.  

  1. Take notes

Each testing company offers an interface for annotating important information about genetic cousins. Researchers might record the exact relationship to an individual once it is determined when they attempted contact with the genetic cousin, the maiden name of someone using her married name, or the full name of someone using a vague username. They might even note the relationship path between the test taker and the match to aid in future interpretation.  

Even if researchers choose not to record notes in the company interface, they should organize their analysis of relationships using their own note-taking system. They might also create charts to visualize relationships between genetic cousins such as the Smart Art chart shown here.  

Exploration of Shared Matches
Exploration of shared matches to genetic cousins can help in the organization of matches into clusters of related individuals. Research can then focus on groups of matches most likely pertinent to a research question. Shutterstock license.

  1. Search and filter

Each company offers several sets of search functions and filters to aid in organizing and interpreting match lists. Users can search for surnames reported in family trees, usernames, or ancestral surname lists. They might search for locations where their ancestors lived. They might filter the list based on shared DNA, shared ethnicity admixture regions, when an individual appeared as a match, or where a match currently lives.

Exploring these filters can help identify more distant matches who may be related through particular ancestral lines or may share surnames or localities of interest in their family trees.

  1. Explore other company tools

Besides the research avenues listed above, each company offers additional features and tools to aid in the analysis and interpretation of DNA test results. 23andMe offers reports on Y-DNA and mtDNA haplogroups, which might suggest further insights, and reports on physical traits and health information, depending on the test purchased.

Ancestry offers a dot-labeling feature for organizing matches into groups. Its ThruLines seek to identify all genetic cousins in a list showing descent from the reported ancestors of the test subject.

MyHeritage offers an AutoCluster tool to help identify clusters of genetic cousins. Its Theories of Family Relativity generate hypotheses of potential relationship paths between a test taker and genetic cousins.

FamilyTreeDNA, 23andMe, and MyHeritage all offer chromosome browsers to aid researchers in determining and analyzing exactly which segments of DNA are shared between test takers and their matches.

Conclusion

These are some of the first steps a researcher might take when exploring newly processed autosomal DNA test results. In future articles, I will describe each step in more detail and explore other options for using DNA test results to solve genealogical problems.  

Getting a DNA test is a great way to start your genealogy journey; however, completing that journey requires hard work and access to the latest tools and services. If you’ve taken a test and need assistance analyzing the results, or if you have a genealogy question you think DNA might be able to answer, we would love to help! Contact us today for a free quote!

 

References

  1. Paul Woodbury, “Foundations for Genetic Genealogy Success: Profiles and Family Trees,” NGS Magazine, October-December 2020, 61.
  2. Jonny Perl, “The Shared cM Project 4.0 tool v4,” DNA Painter (https://dnapainter.com/tools/sharedcmv4, accessed 11 February 2021).
  3. Endogamous populations have been isolated historically due to geography, language, or religion, resulting in multiple shared ancestors or descent from the same ancestors multiple times. Consequently, a large number of genetic cousins share DNA with many other members of the endogamous population, perhaps through independent relationships.

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Where to Test? Genetic Genealogy Testing Options

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 four major DNA testing companies’ tools and their benefits. The article is published here with permission.

Four major DNA testing companies offer genetic genealogy testing—23andMe, AncestryDNA, FamilyTreeDNA, and MyHeritage— and there are several smaller testing companies. Each company has unique benefits, advantages, and insights to offer the serious genealogist.

This article reviews (in alphabetical order) each of the major companies and some of the features they offer as of late 2020. For more detailed and continually updated comparisons of testing companies, read the International Society of Genetic Genealogy’s “Autosomal DNA Testing Comparison Chart.”*

23andMe

23andMe provides a $99 autosomal DNA test dedicated to ancestry analysis and a health + ancestry test for $199. Though the main focus of the ancestry test is autosomal DNA, 23andMe tests also include data regarding the X-chromosome, Y-DNA, and mitochondrial DNA haplogroups. More detailed analysis of the underlying data is possible through the browse raw data and download raw data functions.

23andMe ethnicity chromosome painting
The 23andMe ethnicity chromosome painting shows not only ethnicity admixture percentages, but also which segments of DNA originated from particular populations. © 23andMe, Inc. 2020. All rights reserved and distributed pursuant to a limited license from 23andMe.

With twelve million customers, 23andMe maintains the second largest database of tested users. The company sells kits in fifty-six countries leading to decent representation from international populations. Connecting with users who have tested at 23andMe is possible by opting into the DNA Relatives features of the database. In establishing a profile, users have significant control over the information that is available to matches.

Ethnicity estimates at 23andMe are widely regarded as among the most useful for genealogical research given their general accuracy and the company’s ethnicity chromosome painting which enables the formulation of hypotheses of relationship. For example, if two large segments of DNA in the same overlapping region on both of an individual’s chromosomes are assigned the same ethnicity admixture, it is likely that both parents have ancestry from that region. Alternatively, if a particular ethnicity is only found in long segments on a single copy of each chromosome pair, it is likely that only one parent has admixture from that particular region.

Ethnicity assignments on the X-chromosome or X-chromosomes can help in understanding which lines may be the source of DNA from unique ethnic regions. Recent updates have aided in tying ethnicity estimates to specific countries, regions, and communities. The company permits users to download segment data associated with ethnicity estimates.

The 23andMe match list is currently capped at fifteen hundred matches. For more matches, it is necessary to purchase an upgrade. Filters for the match list enable users to search for individuals not only by username, surname, ancestral surname, or ancestral location, but also by haplogroup, though some filters are currently only available in the upgraded version. Other unique features of the 23andMe interface include its Family Tree view of a match list which incorporates amounts of shared DNA and haplogroup data to estimate how matches might fit into a larger family tree, thus offering a head start on hypothesized relationships.

23andMe Family Tree
23andMe’s Family Tree view of the match list considers amounts of shared DNA between a test subject and matches, amounts of shared DNA between matches, and haplogroup data to estimate the nature of genetic relationships and the structure of a test taker’s family tree relationships with close matches. © 23andMe, Inc. 2020. All rights reserved and distributed pursuant to a limited license from 23andMe.

One of the strengths of the 23andMe platform is the ability to determine which genetic cousins are shared in common with a test subject and the amounts of DNA they share with each other. Another advantage is the ability to perform direct shared segment comparisons between individuals who are sharing genomes with a test subject or who are participating in open sharing.

In terms of segment analysis, 23andMe is the only testing company to report the presence of fully identical regions shared between two individuals, which assists in the evaluation of sibling relationships. These features of chromosome comparisons make 23andMe particularly helpful when working with the test results of individuals belonging to endogamous populations.

AncestryDNA

The $99 AncestryDNA test is an autosomal test dedicated to ancestry analysis. An AncestryHealth test which includes all ethnicity and matching features is available as an upgrade from the AncestryDNA test or as a separate kit option. While the test includes markers from the X-chromosome, Y-chromosome, and mtDNA, only autosomal DNA is utilized in the creation of reports. Raw data is downloadable from Ancestry, but match list data is not.

With more than eighteen million customers, AncestryDNA has the largest database of tested users. AncestryDNA kits are sold in thirty-four countries including the United States, Canada, Australia, and much of Europe. Currently, its strongest markets are in English-speaking countries.

Connecting with other users who have tested is possible through Ancestry’s messaging system and inclusion in match lists. Unlike other companies, AncestryDNA does not share information regarding the exact underlying segments of DNA shared between a test taker and matches—a feature that some consider an advantage given the medical, physical, and other traits that can sometimes be inferred based on shared segment data.

Ancestry DNA tools
AncestryDNA provides tools for organization and clustering with colored dot labels. This example shows how one researcher used dots to assign genetic cousins to particular branches of his family tree. Courtesy of Ancestry.

AncestryDNA offers easy and straightforward means of sharing match list information with collaborators working on the same research problems. Descendants of a research subject inherit different portions of that individual’s DNA, so obtaining access to the test results of multiple descendants can help in achieving a clearer picture of relationship patterns.

AncestryDNA’s ethnicity estimates are helpful for genealogists given their continuous development and improvement in accuracy. In particular, the Genetic Communities feature is helpful for identifying recent migrations and groups with which an individual’s ancestors may have been associated.

Match lists at AncestryDNA are limited to those sharing more than 8 centimorgans of DNA with a test subject. Sophisticated matching algorithms help to prioritize the most pertinent matches based on shared DNA and cutting out shared DNA on unreliable segments or in pile-up regions. Recently, as part of the match list experience, AncestryDNA also has provided information on pre-algorithm total shared DNA, longest segments, and probabilities of relationship based on shared DNA.

AncestryDNA includes features for sorting, labeling, clustering, and otherwise organizing DNA matches using colored dots. Using these labels, it is possible to organize matches based on their relationships to each other into clusters of related individuals. Once organized, these groups can be further explored to identify common ancestors, surnames, locations, or populations connecting the members of a group.

Thru Lines
Family trees attached to the test results of AncestryDNA customers fuel the creation of ThruLines reports, which show the connections between genetic cousins and a test subject even when those genetic cousins have limited family trees. Courtesy of Ancestry.

Because AncestryDNA is part of the Ancestry company, the integration of records, family trees, and matching technologies greatly enhances the AncestryDNA experience. When users attach family trees to their test results, these trees generate shared ancestor hints and shared surname and location hints. The ThruLines feature enables discovery of relationship hypotheses based on family trees of genetic cousins regardless of the size of those trees. Even if a match’s family tree is limited, Ancestry can use data from its large collection of user-submitted trees to extend ancestral lines to identify possible connections and hints for review.

FamilyTreeDNA

FamilyTreeDNA is the only genetic genealogy testing company to offer Y-DNA tests and mitochondrial DNA tests that are genealogically conclusive; it also offers tools for interpretation and evaluation of Y-DNA and mtDNA evidence. Its most advanced Y-DNA test, Big-Y, enables customers to participate in ongoing research and refinement of the human Y-chromosome phylogenetic tree. Besides Y-DNA and mtDNA tests, the company offers a $79 Family Finder autosomal DNA test. While it has not entered the health testing market, FamilyTreeDNA has opened up to collaboration with various law enforcement agencies. Though this development has raised concerns for some, others deem this development an advantage and a benefit.

Family Tree DNA
FamilyTreeDNA is the only company that offers genealogically useful Y-DNA and mitochondrial DNA tests in addition to autosomal DNA offerings. Courtesy of FamilyTreeDNA.

Although FamilyTreeDNA maintains a smaller database of autosomal DNA test results (just over one million customers), the fact that its test is sold in most countries and territories results in a more international customer base. The ability to transfer test results to FamilyTreeDNA from other testing companies provides an easy and cost-effective way of exploring another testing pool or taking advantage of segment analysis tools not available elsewhere. While other companies limit communication with matches to in-house systems, FamilyTreeDNA enables connection between researchers through direct contact information.

Recent updates to FamilyTreeDNA ethnicity admixture reports have improved the estimates. In contrast to other companies that report shared ethnicities between matches as part of the match list, FamilyTreeDNA includes this information in its ethnicity report.

In addition to filters and sorting mechanisms available at some other companies, the FamilyTreeDNA matchlist enables sorting by largest segment, matches shared in common with a subject and a match, and matches not shared in common with a subject and a match. Filtering by largest segment can be helpful when working with test results for individuals in endogamous populations. Filtering match lists by individuals shared in common or not in common with a particular match can be helpful for quickly identifying other individuals likely related through the same ancestral line as the match as well as ancestral lines other than the line on which the match is related.

FamilyTreeDNA’s chromosome browser offers the opportunity to compare segment data (including X-DNA) and permits application of different centimorgan thresholds. This application is useful for cutting out the small segments FamilyTreeDNA includes in the calculations of total shared DNA and for raising thresholds to higher levels for evaluation of pertinent matches in endogamous populations. The chromosome browser also enables downloads of all segment data shared with genetic cousins which can be analyzed in spreadsheets.

Mayflower Project
FamilyTreeDNA provides platforms for collaborative projects with surname, geographic, haplogroup, and other focuses. For example, the Mayflower project managed by the General Society of Mayflower Descendants is dedicated to identifying the Y-DNA and mtDNA haplotypes of Mayflower passengers and their direct line descendants. Courtesy of FamilyTreeDNA.

FamilyTreeDNA offers platforms for collaborative group projects run by volunteer administrators. The subjects of these collaborative projects include surname studies, geographic localities, haplogroups, and descendants of particular individuals.

MyHeritage

The $79 MyHeritage DNA test is an autosomal DNA test. The platform tests markers on the Y-chromosome, X-chromosome, and mtDNA, but these details are not included in customer reports. As with other companies, MyHeritage permits downloads of raw data and match data.

Triangulated DNA Segments
The MyHeritage chromosome browser tool enables true triangulation analysis: identification of segments of DNA shared between a test subject and at least two other DNA matches. Courtesy of MyHeritage.

While MyHeritage is a relative newcomer to the genetic genealogy testing scene, it has experienced remarkable growth. As of late 2020, more than four million customers had tested in their database. Since MyHeritage markets and ships worldwide, the company often holds the best matching results for individuals outside English-speaking countries. Like FamilyTreeDNA, MyHeritage accepts transfers of autosomal DNA data from other testing companies, offering an easy and cost-effective means of exploring another testing pool or taking advantage of additional analysis tools.

Connecting with other users at MyHeritage is possible through its integrated messaging system. The company does not offer the option to share access to test results, but its transfer system permits management of multiple kits under a single account. In this way, MyHeritage enables exploration of research questions from the unique perspectives provided by different descendants of a research subject.

Examples of Autoclusters
The MyHeritage Auto Cluster, provided to users through collaboration with Jan-Evert Bloom of Genetic Affairs, is an excellent resource for quickly grouping genetic cousins into meaningful groups for meaningful analysis of shared ancestors, surnames, locations, and populations. Courtesy of MyHeritage.

Since MyHeritage offers access to documentary research collections and offers tools for tree-building, its database has a relatively high percentage of tested customers with attached family trees to aid in interpretation of relationships. Ethnicity estimates at MyHeritage are in a process of continual refinement and include some categories not found elsewhere, including differentiation between unique Jewish populations.

MyHeritage match lists offer a range of analytical tools, filters, searches, and sorting options. When users connect their test results to family trees, it is possible to generate Theories of Family Relativity, SmartTree Matches, and lists of shared surnames and locations. Theory of Family Relativity analyzes the family trees of a subject and the family trees of matches and identifies possible connections between them through the assistance of other trees and record collections. MyHeritage not only reports which genetic cousins are shared matches but also identifies how much DNA those individuals share with each other. This feature is particularly helpful for prioritization of matches in endogamous populations.

The MyHeritage chromosome browser tool enables identification of truly triangulated segments (segments of DNA that a test subject and at least two matches share with each other). MyHeritage has also partnered with developer Evert-Jan Bloom of Genetic Affairs to provide cluster reports for users through the AutoCluster feature. Relationships between genetic cousins are identified as colored squares in a matrix and are grouped with other individuals who share the same matches. Clusters are often composed of individuals who descend from the same ancestral couple or who have ties to the same community or population. Analysis of clusters can assist in identifying which genetic cousins are related through which family lines and which might be pertinent to a research question.

Where to test? Everywhere!

Due to the unique features, tools, and insights that test-takers can obtain at various companies as well as the different genetic cousins with whom they might connect in the separate testing pools, there is a benefit to testing at any and all of the major DNA testing companies.

This article summarizes the nuts and bolts of pricing, testing types, database size, international reach, collaboration opportunities, ethnicity estimates, match list features, and analysis tools. Other considerations that might guide testing choices include privacy options, involvement with third parties (health, pharmaceutical, and law enforcement), and sampling methods.

As the major testing companies and perhaps other companies continue to develop and grow in the future, it is likely that additional considerations will affect prioritization of which company or companies to utilize for genetic genealogy research. For now, the unique advantages of the major companies merit consideration of testing at each or at least testing and transferring into all four databases.

Getting a DNA test is a great way to start your genealogy journey; however, completing that journey requires hard work and access to the latest tools and services. If you need some assistance, our genealogists will work with you to discover your family history. Contact us today for a free quote!

*“Autosomal DNA Testing Comparison Chart,” International Society of Genetic Genealogy Wiki (https://isogg.org/wiki/Autosomal_DNA_testing_comparison_chart : accessed October 2020).

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Foundations for Genetic Genealogy Success: Profiles and Family Trees

Our own Paul Woodbury follows up on his article about the journey of a DNA sample with a discussion of how profiles and family trees are the foundations for genetic genealogy success.  This article is a reprint from a recent issue of the National Genealogical Society Magazine and is published here with permission. 

In my previous article, ”From Spit to Screen: The Journey of a DNA Sample” I described the journey of a DNA sample from the moment a sample is taken to the moment a test taker receives notification that their test results are ready for review. From mailing to completion of processing, a customer may need to wait several weeks or months until their test results are ready to be used for genealogical research. Still, even while waiting, test takers can perform several tasks to create a strong foundation for future genetic genealogy research success. Creating a detailed profile, preparing lists of ancestral surnames or locations, and uploading a family tree can encourage collaboration, open doors of discovery for others. These steps can also lead to efficient corroboration of proposed family trees, and spur genealogical discovery once test results complete processing.

DNA Profile
A detailed profile can help avoid unwanted communication centered around questions of identity and instead guide and invite collaboration on research topics and families of interest.

A test taker's profile is akin to a job application or resume; it is a tool that helps convince genetic cousins that they do want to work and collaborate with the user. Collaboration is an essential element of all genealogical research, including genetic genealogy, where many genealogical mysteries are solved using the details, information, and family trees shared in the profiles of genetic cousins. While a strong profile can certainly help others in their journeys of genealogical discovery, it can also help a user themselves, by encouraging and inviting efficient and focused collaboration. Each DNA testing company offers the option to customize a profile with an image, description, and explanation of research interests.

When a test taker's profile includes a photo, genetic cousins may consider the user more approachable and open to contact. When a test taker's profile includes additional details such as age, residence, interests, family surnames, or other information, this can help other genetic cousins avoid unnecessary communication just to figure out a user's identity. As a result, those with more complete profiles often experience less unwanted communication centered around identity and instead invite more helpful communication centered around specific research questions and goals for genealogical research. At the same time, the information that a user wishes to share should be balanced against their privacy preferences and comfort level.

In addition to profile images and descriptions, each DNA testing company offers additional options to enhance a user's profile:

23andMe

At 23andMe, users have the option of publishing their current residence, places where their ancestors were born (including survey results regarding their four grandparents), surnames in their family tree, and links to online family trees at other sites. While 23andMe prompts users to fill out these profile items when they are setting up an account, these responses can be edited at any time by reviewing and editing a user's account settings and their ”enhanced profile.” The current residences reported by 23andMe customers in their profiles are used to create the map view of a user's genetic cousin match list: a demonstration of the geographic distribution of genetic cousins.

The results of the grandparent birthplace survey are published on user-profiles and can aid others in quickly determining which ancestral lines may be the source of a shared relationship. In addition to the results of this survey, users can publish a list of other birthplaces from older generations. These, too, are published on a user's profile and are searchable within the database of genetic cousins. For example, performing a search at 23andMe in the ”DNA Relatives” list for ”Alabama” will return all individuals who have reported Alabama as a birthplace for one of their ancestors.

23andMe customers may also provide a list of family surnames in conjunction with their test results. These surnames are also searchable in the general database, along with the names of genetic cousins. For example, a search of the ”DNA Relatives” list for the Woodbury surname will return all individuals with the Woodbury surname listed in their profile of ancestral names. Still, it will also return all matches carrying the Woodbury surname regardless of whether it is included in their profile list or not. 23andMe users can provide a link in their profile to an online family tree. Because 23andMe no longer supports their tree-building tools, users must link their family tree to outside sources. These links can greatly assist others in identifying common ancestors and determining the nature of a genetic relationship. Finally, 23andMe customers can share an introduction and description to be published and shared with their matches.

23andMe Relatives Map
When users at 23andMe report their current residence, it enables other users to analyze the geographic distribution of their genetic cousins.

Users can adust other publication preferences at 23andMe in the settings and preferences for a user's involvement in the DNA Relatives database. These adjustments include how your name is shown, whether or not to display your birth year, the sex you wish to be displayed, as well as if you would like to display your ethnicity percentages and matching DNA segments. These latter display features can be helpful to others in determining the nature of a relationship.

MyHeritage

Users of MyHeritage are asked to fill out a member profile that displays their age and country of residence. Nevertheless, the most useful foundation and preparation that test-takers can pursue here is linking a family tree to their test results. When MyHeritage test-takers link a family tree to their test results, the website will generate hints regarding shared ancestors (SmartMatches) between the trees of common matches. MyHeritage's Theory of Family Relativity will also take the details from trees and compare them against their larger database of trees and records to propose theories of how two individuals might be related. The details are compared even if the proposed common ancestors between two individuals are not included in their respective family trees. When MyHeritage users attach family trees to their test results, the website will also generate lists of shared surnames and shared ancestral locations described in the match list and match profiles. Users can search for specific surnames or can filter by shared surnames or locations.

MyHeritage Match
When a user and their genetic cousin both attach family trees to their DNA test results at MyHeritage, the website will report lists of common surnames, Smart Matches, and common ancestral locations as part of that genetic cousin’s entry in the match list and genetic cousin profile.

Ancestry

At Ancestry.com, customers can adjust their account profile to show their age, residence, languages, family history experience, and research interests. These details can help encourage collaboration and correspondence with researchers sharing similar interests. Publishing residences also enables the map view of DNA test results where users can see the geographic distribution of their genetic cousins.

Ancestry DNA ThruLines
When users attach family trees to their test results at Ancestry, the website will generate ThruLines reports of other genetic cousins also descending from commonly reported ancestors.

Beyond the basic member profile, users can also adjust settings related to how they appear in others' match lists as part of the DNA settings, including their display name and if other users can see their ethnicity estimate and genetic communities.

Perhaps the most useful setting at AncestryDNA is the ability to link a test to a family tree. AncestryDNA will generate hints regarding shared ancestors with other genetic cousins when users link family trees to their DNA test results. They will also present genetic cousins who also descend from shared ancestors as part of their ThruLines tool. AncestryDNA's ThruLines incorporates data from the family trees of matches and utilizes other family trees to link matches to each other even if their common ancestor is not in both family trees. Finally, when users link a family tree to their AncestryDNA test results, Ancestry will highlight shared surnames and locations in the family trees of other genetic cousins, offering clues regarding likely sources of shared DNA. These shared surnames and shared locations are searchable as part of the AncestryDNA search and filter functions.

Family Tree DNA

Family Tree DNA customers can fill out a profile, introduction, and other associated information in their account settings. Customers here should ensure that they publish an updated email address to enable communication with DNA matches. Family Tree DNA also offers the option to select an account beneficiary who can continue to manage the account and any remaining DNA sample if a test taker dies.

Family Tree DNA Bolded Surnames
When a user and their genetic cousin both publish lists of ancestral surnames at Family Tree DNA, shared surnames between the user and their match will appear in bold on the user’s match list.

Under the ”Genealogy” section of Family Tree DNA's account settings, users can add a list of ancestral surnames and associated locations as well as information on their earliest known maternal and paternal ancestors. Surname and location information is beneficial when exploring genetic cousin match lists as any surnames shared in common between a test taker and a match is listed in bold. These surname lists can also be queried as part of Family Tree DNA's surname searches and filters. Meanwhile, user-provided information on the earliest known paternal and maternal relatives can greatly aid in the interpretation of Y-DNA test results and mitochondrial DNA test results. Y-DNA is inherited from father to son in a direct line of paternal inheritance. Mitochondrial DNA is inherited from a mother to her children in a direct maternal line of inheritance. Therefore, one should focus on the earliest known patrilineal (the father of the father the of father) ancestor and earliest known matrilineal (the mother of the mother of the mother) ancestor as opposed to the earliest known paternal relative or the earliest known maternal relative from any ancestral line.

Finally, Family Tree DNA offers the option to upload or build a family tree to associate with a user's test results under the ”MyTree” section. Surnames included in a tree are not searchable in the Family Tree DNA database as the surname lists are. Also, the inclusion of a family tree does not generate automated hints at Ancestry or MyHeritage. Nevertheless, searches can be performed in individual trees for specific names or surnames to quickly locate the position and identity of a common ancestor. Thus, the inclusion of family trees at Family Tree DNA can still help others better determine the nature of their shared relationship to a test taker.

Profile and Family Tree

Setting up a detailed profile at each DNA testing company and, where possible, attaching a family tree to DNA test results lays a strong foundation for future success in genetic genealogy research efforts. A well-crafted profile can direct and invite desired collaboration. The inclusion of residence information can reveal the geographic distribution of DNA matches. Lists of surnames and ancestral locations can generate hints and enable database searching for others. Finally, linked family trees can generate hints of relationship, ease interpretation of key genetic cousins, and aid in identifying which genetic cousins are most likely related through ancestral lines of interest. Users should only share after considering their comfort level and privacy preferences, and each company provides multiple options for setting individual preferences to align with personal privacy concerns.

Regardless of how much a user chooses to share or not share, consideration of these steps stands to benefit all genetic genealogy researchers. As more test takers share details regarding their age, residence, origins, ancestry, and genealogy, all benefit from more readily helpful information, which unlocks the doors to genealogical analysis, interpretation, and discovery.

Getting a DNA test is a great way to start, but completing the journey requires hard work, collaboration, and access to the latest tools and services. If you get stuck and need some assistance, our genealogists will work with you to find success. Contact us today for a free quote!

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From Spit to Screen: The Journey of a DNA Sample

One of our researchers, Paul Woodbury, describes the journey of a DNA sample from the instant the sample is taken until it is analyzed in the laboratory.  The following article is a reprint from the July-September 2020 issue of the National Genealogical Society Magazine and is published here with permission. 

23andme Collection Kit
This 23andMe collection kit and similar AncestryDNA collection kits rely on saliva collection. Hong Chang Bum, “IMG_0901” (https://www.flickr.com/photos/hongiiv/3128937011). Attribution-NonCommercial-NoDerivs 2.0 Generic (CC BY-NC-ND 2.0) license.

How does DNA testing actually work? How can spitting into a tube result in an ethnicity estimate, a list of genetic cousins, and other DNA data? This article reviews the technology that enables genetic genealogy and the five-step process that transforms a saliva sample into a comprehensive genetic report: collection, extraction, amplification, testing, and data analysis (1).

Collection

Complete copies of the human genome are carried by most of the trillions of cells in the human body. While red blood cells and some skin, hair, and nail cells do not carry nuclear DNA, nearly any other type of cell can be sampled for DNA analysis.

In the early days of genetic genealogy testing, companies utilized blood samples. Now, most genetic genealogy testing companies collect DNA through less invasive and more convenient spit or cheek swab kits. The DNA obtained from these kits originates from white blood cells in saliva and buccal epithelial (cheek) cells.

Most DNA testing companies discourage testers from eating, smoking, drinking, chewing gum, brushing teeth, or using mouthwash in the half-hour before taking a DNA test. While foreign particles from food, liquids, toothpaste, and tobacco do not alter DNA, they can mask it or cause it to degrade(2).

Testing companies also warn against activities that might cause cross-contamination of a sample. For swab collection kits like those used by Family Tree DNA and MyHeritage, testers should be careful not to drop the swab in anything that might contaminate the sample, touch the collection swab with their hands, or brush it against other objects. When performing spit collection tests like those utilized by AncestryDNA and 23andMe, testers should try to collect all the necessary saliva at once to avoid contamination from foreign materials in the air.

DNA testers should register their kit with the corresponding testing service to ensure later access to the test results. Some labs will not process kits that have not been registered.

National Geographic Collection Kit
This now obsolete National Genographic collection kit is similar to Family Tree DNA and MyHeritage collection kits which rely on buccal swabs. Paulo O, “Genographic Kit andAntares info kit” (https://www.flickr.com/photos/brownpau/8653415433). Attribution 2.0 Generic (CC BY 2.0) license.

While DNA can sometimes last very long in the right environment, degradation can occur due to proteins that destroy DNA, foreign materials like food, bacteria, and other chemicals, or large fluctuations in temperature. To prevent degradation and to keep DNA intact from the time it is collected to the time it is ready to be analyzed, sample collection kits typically include a liquid buffer solution.

These solutions stabilize the cells, sometimes include antibacterial elements, inhibit the activity of proteins that would degrade the DNA, and preserve the DNA in a stable pH solution which is not as easily affected by fluctuations in temperature. With such a solution, DNA can be preserved while it is prepared, mailed, stored, and eventually processed by a lab.

Isolation and Extraction of DNA

Every DNA collection sample has hundreds of thousands of cells, each carrying a copy of the tester’s DNA, but these samples also contain proteins, chemicals, fats, water, and a host of other biological materials. Before DNA can be analyzed, it must be isolated from all of these other materials.

First, cells are broken open with a detergent. Cells are held together by a membrane composed of two layers of fat called a lipid bilayer. Just as detergents interact with fats in water, they interact with the lipids in cell membranes to break them open and release the contents of the cell into a solution.

Next, certain cellular components are destroyed. Cells carry proteins that interact with DNA as well as other proteins that destroy free-floating DNA. Cells also include free-floating RNA, which is similar to DNA and can cause problems in later DNA analysis. To overcome these problems, a protease (an enzyme that destroys proteins) and an RNAse (an enzyme that destroys RNA) are added to the sample.

Finally, salt is added to the mixture to make all the debris from the proteins, lipids, and RNA clump together. When the solution is centrifuged (spun in a circle at very high speeds), this debris clumps together and collects at the bottom of a sample tube, leaving the DNA floating in the solution.

After most of the debris is removed from the sample, the DNA is further isolated from the detergents, proteins, salts, and reagents used in the first step. Alcohol is added to the sample, and since DNA is insoluble in alcohol, a subsequent round of centrifuging isolates the DNA in a clump at the bottom of the test tube. The DNA has been isolated.

Polymerase Chain Reaction
In order to obtain a sufficient amount of DNA for testing, companies amplify the DNA from the original sample through Polymerase Chain Reaction protocols. Enzoklop, “Polymerase chain reaction” https://commons.wikimedia.org/wiki/File:Polymerase_chain_reaction.svg). Creative Commons Attribution-Share Alike 3.0 Unported license.

Amplification

The technologies used by genetic genealogy testing companies require a large amount of DNA for successful analysis—much more DNA than what is present in the initial sample provided by a customer. For this reason, labs utilize Polymerase Chain Reaction (PCR) protocols to amplify or copy the DNA being analyzed. DNA replicating proteins, free-floating DNA bases, and DNA primer sequences are added to a sample to create an environment conducive to DNA replication.

Next, the sample is submitted to several cycles of temperature variations. During this process, the DNA denatures or “melts” into single strands, DNA primers bind to complementary strands of DNA, and DNA polymerase (a DNA-building and replicating protein) recruits free-floating bases and extends the DNA, making a new copy.

In the first temperature variation cycle, one strand of DNA duplicates into two strands. The number of copies of the DNA doubles with every cycle, and within a few hours, it is possible to obtain millions of copies of a test taker’s DNA from the initial sample.

Testing

At this point, the way in which DNA is tested depends on the type of DNA test being performed. Autosomal DNA tests, Y-DNA tests, and mtDNA tests are treated differently. Because autosomal DNA testing is the most common type of testing, this article reviews the protocols for SNP chip microarrays.

Single Nucleotide Polymorphisms (SNPs) are locations in DNA that are known to be hotspots of variation in the general population. Rather than testing all of an individual’s DNA, testing companies typically test between 400,000 and 700,000 SNP markers across the genome. Because each individual has two copies of DNA—one from the mother and one from the father—there are three possibilities for a genotype at any given SNP marker: both copies could carry one variation, they could both carry the other variation, or they might carry different variations.

For example, if an SNP marker has two typical values of C or G, it is possible that an individual could have a genotype of CC, GG, or CG. An individual with the same SNP variation on both copies of DNA is homozygous at that location. A person with different variations on the two copies of DNA is heterozygous at that location.

Genetic genealogy tests rely on SNP Chip testing to query SNP markers for a test taker. Each testing company uses chips manufactured by Illumina, a biotechnology company. These “chips” are glass plates with microscopic silicon beads attached to predefined and indexed locations(3).

Each silicon bead, in turn, has several copies of a manufactured short single-stranded segment of DNA attached to it. These short sequences are complementary to a sequence in human DNA immediately preceding the location of a SNP.

In order to test SNP locations, a tester’s sample is treated to shear or break the DNA into smaller fragments and denatured to make it single-stranded. Next, the DNA is washed over the chip, where it binds with the complimentary manufactured DNA just short of the location of the SNP. Then DNA Polymerase and modified A, T, G, and C nucleotides with fluorescent tags are introduced. The sample DNA is washed away, leaving the manufactured strands with one more base and fluorescent tags indicating which base has been added.

The chip is then submitted to a laser reader, which causes the DNA strands to fluoresce red (homozygous for one variation), green (homozygous for the other variation), or yellow heterozygous). A scanning software records and interprets the fluorescence. It determines the color of each locus, determines what the fluorescence means for that location, and then uses the index to associate the result with a corresponding location in the genome.

Finally, the software program records the values, A, T, G, or C, that have been detected for each of the 500,000-700,000 locations that have been analyzed into a raw data file.

Laser Scan DNA
Once the DNA has been extended by one fluorescently labeled base, it is submitted to a laser scan. Green indicates homozygosity for one version of the SNP, red indicates homozygosity for the other version of the SNP, and yellow or orange indicates heterozygosity. Each color for each site is interpreted by software and associated with a particular location in the genome. Kat Masback, “Microarray, AV-0101-5194 Dr. Jason Kang, NCI (Lance Miller)” (https://www.flickr.com/photos/36128932@N03/3341761068). Creative Commons Attribution-ShareAlike 2.0 Generic license.

Data Processing

Autosomal DNA raw data results are composed of a list of several hundred thousand marker locations and two base values (A, T, G, or C) for the corresponding locations (one maternal and one paternal). In and of themselves, these values have limited usefulness for genealogical research. It is a comparison against reference datasets and customer databases that generate the most useful elements of genetic genealogy tests: ethnicity admixture estimates and cousin matching.

Ethnicity admixture estimates for autosomal DNA tests are obtained by comparison of a raw data file against a “reference panel” of samples for individuals with known ancestry from particular regions of the world. Prevalence of DNA marker values in specific populations is used to assign portions of a test taker’s DNA to different ethnicities or regions.

Autosomal DNA matches are identified by comparing the markers of a test subject against the markers of other tested customers in the database. When two individuals share long sequences of consecutive markers on at least one DNA copy, they share a “segment” of DNA from a recent common ancestor. Based on the size, location, and the number of segments two individuals share, it is possible to estimate how closely two individuals are related to each other.

Conclusion

Once raw data has been incorporated into a company’s system and compared against other customers and reference datasets, the test taker receives a notification that DNA test results have completed processing. From spit to screen, the DNA sample has been collected, isolated, amplified, tested, and processed to provide the researcher with useful information for a genealogical investigation.

Websites cited in this article were viewed on 8 June 2020.

1. “What Happens To My DNA Sample At The Lab?” 23andMe (https://customercare.23andme.com/hc/en-us/articles/202904590-What-Happens-to-My-DNA-Sample-at-the-Lab).

3. “Infinium™ Global Screening Array-24 v3.0 BeadChip,” Illumina (https://science-docs.illumina.com/documents/Microarray/infinium-globalscreening-array-data-sheet-370-2016-016/infinium-commercial-gsa-ds-370-2016-016.pdf).

Getting a DNA test is a great way to start your genealogy journey, but what comes next? Hire a professional at Legacy Tree and our genealogists will work with you to discover your family history. Contact us today for a free quote!

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The Biological Journey of DNA Inheritance: Meiosis to Fertilization

Understanding the biologial journey of genetic inheritance can help in the interpretation of DNA evidence for genealogy research.

*This article originally appeared in NGS Magazine, and is reprinted with permission.

Different DNA inheritance paths  can help solve genealogical mysteries. These unique inheritance patterns provide important context for interpretation of DNA test results and enable genealogical discoveries, but why is DNA inherited the way it is? What underlying biological processes explain the inheritance patterns of different types of DNA? What are the natural laws that govern genetic inheritance paths?

Genealogists commonly utilize historical, social, governmental and legal context to understand and interpret the records created regarding ancestors. Just as an understanding of the laws of a particular time period and place can aid in interpretation of records created for an ancestor, understanding the biological laws governing genetic inheritance can help in later interpretation of DNA evidence for genealogical purposes.

An Introduction to DNA

DNA is composed of four bases: Adenine (A), Thymine (T), Guanine (G) and Cytosine (C). Long strands of these bases pair with each other (A with T and G with C) to form a double helix. Attribution: Zephyris, “DNA Structure+Key+Labelled,” https://en.wikipedia.org/wiki/File:DNA_Structure%2BKey%2BLabelled.pn_NoBB.png. CC-SA 3.0

DNA provides the blueprint for all life and is written with four biological “characters” called bases: Adenine (A), Thymine (T), Guanine (G) and Cytosine (C). These bases are linked together in long strands to form an “instruction manual” for the human body. To protect this important biological code from damage, the strands of DNA align with complementary strands: A pairing with T and G pairing with C. The result is a double helix structure composed of millions of “basepairs.” A human genome (or a complete set of human DNA) contains approximately 6.4 billion basepairs.

Genetic Records, Archives, Transcription and Translation

The human genome is like an instruction manual that is divided into twenty-three “volumes” known as chromosomes. There are two “editions” of each volume of the instruction manual: a paternal edition inherited from an individual’s father, and a maternal edition inherited from an individual’s mother. The instruction manual also includes an “addendum” of mitochondrial DNA. The twenty-three chromosome volumes which form the majority of the genome instruction manual are housed as a single collection in an “archive” called the nucleus. The mitochondrial DNA addendum, meanwhile, is stored outside of the nucleus in locations called mitochondria.

Most human DNA, including a copy of all twenty-three pairs of chromosomes, is stored in the nucleus of the cell which serves as a type of cellular archive. Meanwhile, each mitochondrion has multiple copies of the mitochondrial DNA and most cells have multiple mitochondria. Attribution: OpenStax, “Animal Cell and Components,” modified, https://commons.wikimedia.org/wiki/File:0312_Animal_Cell_and_Components.jpg. CC-A 4.0

The human body is composed of trillions of cells and each of those cells (with a few exceptions) has a nucleus with a copy of the paternal and maternal editions of all twenty-three chromosome volumes. Each cell also has multiple mitochondria which serve as cellular powerhouses; each mitochondrion carries multiple copies of the mitochondrial DNA addendum. Though each cell contains a complete genome instruction manual, only parts of the manual are read depending on the type of cell. As with historic archives, consultation of the original DNA records is not possible outside of the nucleus archive. Instead portions of the DNA instructions read by specialized protein machines which “transcribe” select portions of the genome into RNA copies. These RNA transcriptions can be distributed outside of the archive and “translated” into sequences of amino acids. Chains of amino acids interact with each other to form proteins. The shape of proteins governs their function. Processes for reading, transcribing and translating mitochondrial DNA are similar to those employed in the nucleus.

Portions of the DNA are transcribed in the nucleus into RNA copies, These RNA strands can be transported out of the nucleus and used as a template for translation from RNA code to protein synthesis. Attribution: Dhorspool, “Central Dogma of Molecular Biochemistry with Enzymes,” https://commons.wikimedia.org/wiki/File:Central_Dogma_of_Molecular_Biochemistry_with_Enzymes.jpg. CC-SA 3.0

Mitosis, Meiosis, Mutations

Human bodies grow, change, and develop through the continual replacement and division of cells – a process called mitosis. When a cell divides, the entire genome is copied. Each edition of each chromosome volume is replicated and bound with its duplicate at a part of the DNA strand called the centromere. Then, the nucleus is demolished. Next, a copy of each edition of each chromosome volume is distributed to opposite sides of the cell. Two new nuclei (archives) are built around these new copies of the instruction manual, and the cell then divides into two new cells. Thus, each daughter cell carries a complete copy of the genome. This process of genetic replication and division occurs millions of times each day.

Genetic inheritance and DNA
During mitosis or cell division, DNA is replicated and a complete set of the genome is sent to the two resulting daughter cells. Attribution: Ali Zifan, “Mitosis Stages,” https://commons.wikimedia.org/wiki/File:Mitosis_Stages.svg. CC-SA 4.0

Mitochondria replicate independently within each cell and contain multiple copies of mitochondrial DNA. When a mitochondrion becomes too large, it divides in half. Some copies of the mtDNA are included in one new mitochondrion and some copies are preserved in the other. When a cell divides, some mitochondria remain in one cell and other mitochondria remain in the other.

Given how often the genome is replicated, it is no surprise that sometimes errors are made in the replication of DNA. Some errors or mutations can have a detrimental effect and might lead to cell death. Others might affect the shape of a protein and its resulting function or prevalence. Other mutations have little to no effect and are passed on to descendant cells. The introduction of occasional mutations makes genetic genealogy possible. Any human individual shares approximately 99.9% of their DNA with all other humans. It is the .1% variation between humans and the associated inherited mutations that enable investigation, analysis and determination of the closeness of genealogical relationships.

Usually, when cells divide, a complete copy of the genome is passed on to both daughter cells. However, this is not the case for germ-line cells: sperm cells and egg cells. A process called meiosis results in sperm and egg cells with just a single edition of the genome rather than the two editions held by most other cells. Meiosis starts in much the same way as mitosis. Each chromosome is duplicated so that there are two copies of each edition of each of the twenty-three chromosome volumes. The two copies of each edition are bound together at the centromere. However, instead of separating to opposite sides of the cell, the paternal editions of each chromosome pair off with the maternal editions of each chromosome and become closely associated. A process called recombination often results in parts of a maternal edition of any given chromosome being swapped with corresponding parts of a paternal edition of the same chromosome.

After this exchange of information, the nucleus disintegrates, and the altered editions of each chromosome are pulled to opposite sides of the cell. One set of altered editions is pulled by its centromere to one side of the cell and the other set of altered editions is pulled by its centromere to the other side of the cell. The cell divides and the resulting cells divide again. During this second round of cell division, there is no replication of the editions and instead, an edition of each chromosome volume is pulled to opposite sides of the cell. The result of meiosis is four cells with a single edition of each chromosome volume – half the normal amount carried by most cells. In females, one large egg is created with three smaller cells which typically die. In males, four sperm cells are created. In any given cell the single edition of any given chromosome volume could be the maternal edition, could be the paternal edition, or could be (and often is) a compilation of information pulled from both the maternal and paternal edition of the chromosome.

genetic inheritance DNA
During meiosis, DNA undergoes recombination, and the undergoes two cell divisions. The result is four cells with one copy of each chromosome – half the normal amount for a typical human cell. Attribution: Ali Zifan, “Meiosis Stages,” https://commons.wikimedia.org/wiki/File:Meiosis_Stages.svg, CC-SA 4.0

Sex Chromosomes – Special Editions

Human DNA is divided into twenty-three sets of chromosomes. Each chromosome has two “editions” one maternal and one paternal. 

Chromosome volumes 1-22 are very similar regardless of the edition consulted (maternal or paternal). The paternal and maternal editions of chromosome volume 23, meanwhile, can be quite different. In females, the paternal and maternal editions are X-chromosomes which are fairly similar. In males, meanwhile, chromosome volume 23 has two very different editions: A maternal X-chromosome edition and a much smaller paternal Y-chromosome edition. When meiosis occurs in females, the X-chromosomes line up and undergo normal recombination. The resulting four cells from the process each contain an X-chromosome. In males, meanwhile, the Y-chromosome and the X-chromosome line up but only undergo very limited recombination. Therefore, the Y-DNA and X-DNA are passed on essentially unchanged to daughter cells. Two of the four cells resulting from meiosis in males will contain Y-chromosomes and two will contain X-chromosomes.

Fertilization

During the process of human reproduction, millions of sperm cells approach an egg in a race to fertilize it. When an egg and a sperm combine, they form a zygote which has the potential to eventually develop into a human being – the next generation. If the sperm cell carried a Y-chromosome, then the resulting zygote could develop into a biological male. If the sperm cell carried an X-chromosome, then the resulting zygote could develop into a biological female.

While sperm cells do carry mitochondria and associated DNA, when the sperm cell penetrates the egg, the cellular contents of the sperm (including the mitochondria) are destroyed. Thus, except in rare cases, the only surviving mitochondrial DNA originates from the egg and is thus maternally inherited. The nucleus from the sperm, however, remains intact until it merges with the egg’s nucleus at which point the process of cell division can begin in the development of a fetus.

Genetic Inheritance and DNA: Y-DNA and X-DNA Inheritance

Y-DNA and X-DNA inheritance can be explained by the process of meiosis. In males, this process results in the creation of four sperm, two of which carry a Y-chromosome and two of which carry an X-chromosome. In females, the process of meiosis results in the formation of an egg cell which contains an X-chromosome. If the fertilizing sperm contains a Y-chromosome the resulting fetus will be male. If it contains an X-chromosome the resulting fetus will be female.

X-DNA inheritance and autosomal DNA inheritance can also be partially explained by the process of recombination in which each maternally inherited chromosome aligns with each paternally inherited chromosome and might exchange or shuffle genetic material into novel chromosome variants or editions. As a result, while each individual inherits 50% of their DNA from each parent in the form of a complete set of paternal and maternal chromosomes. Inheritance from more distant generations of ancestors is more random. For this same reason, X-DNA might, but may not necessarily be inherited from a specific subset of ancestors related through maternal lines or alternating maternal-paternal lines.

Mitochondrial DNA inheritance can be explained by the mechanics of fertilization which preserve mitochondria and associated DNA from egg cells but destroy mitochondria and associated DNA from paternal sperm cells.

Understanding these basic laws of genetic inheritance can help in the interpretation of DNA evidence for genealogy research.

Do you have a genetic genealogy mystery you would like help resolving? Contact Legacy Tree Genealogists today. Our team is experienced at utilizing DNA evidence from all major testing companies in combination with thorough records research to break down the genealogy “brick walls” in your family tree. 

Understanding the biologial journey of genetic inheritance can help in the interpretation of DNA evidence for genealogy research.

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The Journey of DNA’s Inheritance Paths: X-DNA and Autosomal DNA

The stories in this article demonstrate how X-DNA and autosomal DNA can be used to solve research problems based on DNA inheritance patterns.

*This article originally appeared in NGS Magazine, and is reprinted with permission

The DNA in humans today has taken a far- ranging journey from ancestors of long ago. The stories in this column demonstrate how DNA can be used to solve research problems based on inheritance patterns. Each human has DNA, a biological code that affects many physical, emotional, and behavioral characteristics. Humans inherit copies of DNA from their parents, who in turn inherited portions of DNA from their parents, grandparents, and other ancestors. The journey that DNA takes from ancestor to descendants, from generation to generation over hundreds of years, follows four major inheritance paths. DNA testing and consideration of these patterns enable researchers to uncover information about their biological heritage. Two inheritance paths, X-DNA and autosomal DNA, are discussed in this article; mitochondrial DNA and Y-DNA were described in a previous article, The Journey of DNA's Inheritance Paths: mtDNA and Y-DNA.

X- DNA

X- DNA is one of the sex chromosomes (the other sex chromosome is the Y-chromosome previously discussed). While a male inherits
an X-chromosome from his mother (which he passes on to his daughters), a female inherits one X-chromosome from her mother and one from her father (and by extension from her father’s mother). When two X chromosomes are present, as is the case in biological females, the two copies align and may exchange genetic material in a process called recombination before being passed on to the next generation of descendants. As a result, the X-DNA that an individual inherits from the mother could come entirely from the maternal grandfather or entirely from the maternal grandmother, or it may be a mixture of the X-DNA carried by the maternal grandfather and the maternal grandmother.
When two individuals share large segments of X-DNA, they share a recent common ancestor at a specific location in their respective family trees. The basic rule of X-DNA inheritance is that it cannot be passed through two successive generations of males. Just because it is possible to inherit X-DNA from a particular ancestor does not necessarily mean that an individual does inherit X-DNA from that person. X-DNA is tested by all companies, but not analyzed by all companies. Due to X-DNA’s unique inheritance pattern, sometimes it can be used to narrow the possible nature of a relationship between two autosomal DNA matches.
X-DNA genetic inheritance patterns
X-DNA can only be inherited from a subset of particular ancestors. It cannot pass through two successive generations of males. Provided by Legacy Tree Genealogists.

The mystery of Johanna’s father

Born in New York City in 1946, Johanna is the daughter of Ethel X-Grussmeyer, an actress and a native of Alsace-Lorraine, France.* Growing up, Johanna knew nothing about her father. Every time she asked Ethel about him, Ethel would tighten her lips and refuse further discussion. Eventually, Johanna decided it was best not to ask. Though Johanna had no knowledge of her father’s identity, origins, characteristics, or family, the 50 percent of her DNA she had inherited from him eventually provided clues to uncover his identity. When Ethel died, Johanna despaired at the thought that she might never learn about her paternal origins, but then she took a DNA test. Her DNA, particularly her X-DNA, connected her to the traces of a parallel genetic journey in her father’s family. Part of the DNA Johanna inherited from her father was an X-chromosome which he, in turn, inherited from his mother, Johanna’s paternal grandmother.

Gustav Algot Fredriksen was born in Copenhagen, Denmark, in 1877, the oldest son of Fredrik Daniel Olsen and Maria Jensen. As part of his genetic inheritance, Gustav inherited an X chromosome from his mother—an inheritance which he shared in part with his six younger siblings. Gustav eventually married Julia, the only daughter of a Swedish couple, and passed on his X-DNA genetic legacy to his only child, Charlotte. In turn, Charlotte passed on parts of Gustav’s X-DNA to her son, Christen, and her daughter, Sofia. In 2017, autosomal DNA testing for Christen and Sofia revealed that they shared large amounts of DNA and large segments of X-DNA with an unknown relative: Johanna Grussmeyer.

Johanna has few other genetic cousins, and none as close as Christen and Sofia, but the shared X-DNA between all three individuals aided in solving the mystery of Johanna’s father. The amount of DNA that Johanna shares with Christen and Sofia suggests they are likely related as second cousins. In other words, they probably share common great-grandparents. Since both Christen and Sophia share X-DNA with Johanna, their shared ancestry has to be through their mother, Charlotte. Because Charlotte had no ancestry from Alsace-Lorraine, their relationship has to be through Johanna’s paternal family, more specifically through her paternal grandmother.

Finally, since Charlotte had only paternal aunts and no maternal aunts, it was clear that a sister of Gustav was the paternal grandmother of Johanna. Gustav had three sisters. One died in infancy. Another had no children. The third had one son named Wilhelm Thorsen, a professional actor who traveled to New York in the spring of 1945. He carried with him X-DNA from his mother, an inheritance he shared with his uncle Gustav and his first cousin Charlotte, and which he passed on to his biological daughter, Johanna. Targeted testing of Wilhelm’s only living son confirmed that Johanna Grussmeyer is the biological daughter of Wilhelm Thorsen.

Charlotte Fredriksen inherited an X-chromosome from her father, which he in turn inherited from his mother Maria Jensen. Charlotte passed on portions of this chromosome to her two children: Christen and Sofia. Based on autosomal DNA, Christen and Sofia are most likely second cousins to Johanna. Since Christen and Sofia share X-DNA with Johanna, they must be related to Johanna through their mother, Charlotte (Christen can only inherit X-DNA from his mother). Since Charlotte has no ancestry from Alsace Lorraine (the home of Johanna’s mother), Christen and Sofia must be related through Johanna’s paternal ancestry, specifically through Johanna’s paternal grandmother.

Key concepts

The concepts for incorporating X-DNA evidence shown in this story include:

  • When a male shares X-DNA with a genetic cousin, their shared ancestor must be one of his maternal relatives.
  • When a female shares X-DNA with a genetic cousin, their shared ancestor could be a maternal relative or could be a relative of her paternal grandmother.
  • Shared X-DNA can help to narrow the potential relationship scenarios explaining the shared autosomal DNA between two individuals.
  • X-DNA is often considered in conjunction with autosomal DNA evidence to better pinpoint likely common ancestors.

Autosomal DNA

Sex chromosomes (a Y chromosome and an X chromosome in biological males and two X-chromosomes in biological females), are just one pair of chromosomes in the nucleus of a human cell. Another twenty-two pairs of nuclear chromosomes constitute an individual’s autosomal DNA. Twenty-two chromosomes come from the mother, and twenty-two corresponding chromosomes of similar shape, size, and composition originate from the father. As with X-DNA, autosomal DNA recombines before being passed on to each subsequent generation of descendants. As a result, any paternally inherited chromosome could have come in its entirety from a paternal grandfather or a paternal grandmother, or it could (and often does) contain DNA from both individuals. The same is true of maternally inherited chromosomes.

Autosomal DNA is inherited from many ancestors across many ancestral lines. Individuals inherit 50 percent from each parent, and approximately half again from individuals in each
preceding generation. Provided by Legacy Tree Genealogists.

While each person inherits exactly half of autosomal DNA from the mother and half from the father, due to recombination the percentages of inherited DNA from more distant generations are approximate: about 25 percent from a grandparent, about 12 percent from a great-grandparent, and about half again from every previous generation of ancestors. Most individuals inherit at least some autosomal DNA from each of their third-great-grandparents. Nevertheless, as researchers trace their family trees further back in time, eventually they will identify ancestors from whom they inherited no autosomal DNA at all. This lack of inherited DNA from more distant ancestors typically begins to occur in the range of fourth- and fifth-great-grandparents.

When two individuals share autosomal DNA, they often share a recent common ancestor or ancestors. Depending on the amount of shared DNA, the position of that DNA on individual chromosomes, and the total number of segments shared, it is possible to estimate the approximate level of a relationship. Additional exploration of genetic cousins shared between two individuals and documentary evidence can help topple genealogy brick walls.

Finding a family for Cora

Cora Sterling was only enumerated in a single surviving federal census. According to the 1900 census of New Orleans, Louisiana, she was born in August 1882 in Mississippi, to a father born in Georgia and a mother who was a native of Mississippi. While Cora may have been enumerated with her parents in the 1890 census, that enumeration was mostly destroyed in a 1921 fire.

Cora’s 1900 census enumeration also reported that sometime in 1899 she had married Vernon Sterling. Despite her recent marriage, no candidates were found in the surrounding households, city, county, or surrounding counties who might be her parents. By 1910, Cora was deceased. Both of the death records of her children reported that her maiden name was Baker—a clue regarding her origins. Although Cora was never mentioned in any document with her parents, she carried a biological record of their identities in her autosomal DNA.

David H. Burr, “Map of Mississippi, Louisiana & Arkansas exhibiting the post offices, post roads, canals, rail roads, &c.,” The American Atlas (London, J. Arrowsmith, 1839). Library of Congress (https://www.loc.gov/item/98688404). Cora Baker Sterling appears to have migrated south from her origins in Madison County, Mississippi, down the Big Black River and the Mississippi River and eventually to Adams County, where her father is reported to have died in 1891 and her sister, Lillie, was married in 1893. Finally Lillie and Cora settled with their families in New Orleans further down the Mississippi.

Enumerated in the same 1900 household as Vernon and Cora was another couple: George and Lillie Brewer. Lillie was born in Mississippi in March 1871 and also reported that her father and mother were natives of Georgia and Mississippi, respectively. An 1893 marriage record stated that George Brewer married Lillie Baker in Adams County, Mississippi, but even the indirect route of assuming a close connection between Lillie and Cora failed to identify parental candidates for Lillie and, by extension, possibly Cora. By 1910, both Cora and Lillie had died, and it seems no vital records were created to document their deaths. Nevertheless, before her death, Cora passed on 50 percent of her autosomal DNA to her two children, a biological legacy that would eventually help identify her parents and siblings.

In 2018, autosomal testing for Cora’s grandson and great-granddaughter showed that they share significant portions of their autosomal DNA with a tested descendant of Lillie Baker Brewer, confirming that Lillie and Cora were indeed siblings. These three individuals all share DNA with many descendants of a Baker family from Madison County, Mississippi.

George Baker and his wife Eliza were enumerated in the 1880 census in Madison County, Mississippi, with nine children, including a daughter named Lillian born about 1871— the same person who would later be known as Lillie Baker Brewer. Descendants of Lillie Baker Brewer and Cora Baker Sterling share significant amounts of DNA with fourteen descendants of five of the other children of George and Eliza, as heirs of this couple’s autosomal DNA legacy. They also share DNA with collateral relatives of both George and Eliza.

While the amounts of DNA that any descendant of Cora or Lillie shares with other descendants of George and Eliza Baker suggests a range of possible relationship levels, consideration of all of the relationships in tandem confirms with very high probability that Cora Baker was the daughter of George and Eliza Baker.

Cora was never mentioned in any record with her parents. No church record, will, census record, or other record names her with her family. Yet the genetic record of her autosomal DNA passed on in part to her descendants and similarly passed down through the families of her siblings, aunts, and uncles confirms what no record states outright.

Key concepts

The concepts for incorporating autosomal DNA evidence shown in this story include:

  • Because the amount of autosomal DNA inherited from an ancestor decreases with every subsequent generation of descent, it is best to test the closest generational descendants of an individual to address a research question.
  • The inheritance pattern of autosomal DNA decreases its effectiveness for exploration of research questions concerning more distant generations.
  • Though the level and nature of a relationship between a descendant of a research subject and a single genetic cousin may be ambiguous, consideration of the shared DNA between a group of descendants of a research subject and a group of related genetic cousins can provide a more exact indication of the likely relationship.
  • Assuming that a couple has no siblings or first cousins that also formed marital alliances between two families, a test-taker’s genetic relationship to collateral relatives of both members of a couple can act as strong evidence that they descend from that couple.

Conclusion

Consideration of the historic journey that Y-DNA, mitochondrial DNA, X-DNA, and autosomal DNA follows from ancestors through multiple generations to the present day can offer insights into the meaning of DNA shared with other testers and aid in solving genealogical mysteries. The universal, uniform, independent, and mutual nature of genetic inheritance makes these genetic journeys useful for tracing corresponding genealogical journeys.

Do you have a genetic genealogy mystery you would like help resolving? Contact Legacy Tree Genealogists today. Our team is experienced at utilizing DNA evidence from all major testing companies in combination with thorough records research to break down the genealogy ”brick walls” in your family tree. 

* Note that while both scenarios in this article are based in real experiences, the names, locations, and details have been changed to protect the identities of living individuals.

 

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Shocking Ethnicity Estimate Leads to Life-Altering Discovery

A surprising ethnicity estimate leads Tom to explore the possibility that the father who raised him was not his biological father.

Sometimes, genetic genealogy test results don’t fit with what you might expect given what you know (or think you know) about your family tree. These anomalies can sometimes be explained by the way in which estimates are generated. Other times, surprising ethnicity results are instead due to cases of recent misattributed parentage. Such was the case with Tom.  We share his story with permission. 

Tom’s Story 

At 70 years old my wife figured I didn’t need another shirt for Christmas so she bought me a DNA kit. I was in no hurry to send it in as I knew my ancestry. My Mom was Irish on both sides and my Father’s Dad was an Irish immigrant and his Mom was born in Germany. I always just considered myself Irish.  

After much pestering I finally sent it in. The results came back that I was largely Italian. I dismissed that as ridiculous and bought a DNA kit from a different company. When these results came back exactly the same as the first kit, I figured they must copy each other’s results. Still, I was troubled by this. My wife said, “At your age why not just forget it.” But I couldn’t. I had to find out the truth, and if these tests are correct, I had to find out who I am. 

An Unexpected Ethnicity Estimate 

Tom took autosomal DNA tests at several different testing companies. Individuals inherit 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.  

From what Tom knew about his ancestry, he expected to find Irish and German ancestry. When our researchers at Legacy Tree Genealogists reviewed his ethnicity results at several testing companies, we confirmed that while he did have some British and Irish admixture, approximately half of his DNA was found to originate from Southern Europe and North Africa – an admixture profile typical of individuals with ancestry from southern Italy and other Mediterranean populations. Since each individual inherits exactly half of his or her autosomal DNA from each biological parent, Tom’s test results suggested that one of his parents had Italian ancestry, rather than the expected Irish or German. We suspected that either one of Tom’s parents was not his biological parent or that one of Tom’s parents was adopted. Determining which scenario was more likely would require more investigation.  

Tom’s Story 

Determined to find out who I really was, I did a Google search for ‘genealogy research companies.’ After reading reviews, I called Legacy Tree Genealogists. I found them polite and understanding so I hired them.   

When I received my completed research project, it said the man who raised me was not my biological father. My first reaction was negative and upset, but I soon regained my determination to find out who I was. The folks at Legacy Tree were amazing. “These are your paternal grandparents who immigrated to the USA from Sicily,” the report said. One of their sons was my father. 

Examining Genetic Matches for Clues 

While genetic genealogy test results do provide ethnicity estimates that can offer genealogical context and clues, they also include lists of genetic cousins whose relationships are much more useful for proving genealogical connections. Review of Tom’s DNA match lists revealed that not only did he have ethnic admixture linking him to southern Italy, he also had close genetic cousins who descended from a family of Italian immigrants. Based on the relationships between these individuals, it seemed most likely that Tom was also descended from this same family. While Tom had genetic cousins who were related through his known maternal ancestors, suggesting that his proposed mother was indeed his biological mother, he had no genetic cousins who could be identified as relatives of his proposed paternal ancestors, suggesting that the man who raised him was not Tom’s biological father.  

Genetic genealogy testing companies prioritize and organize genetic cousins based on the number of centimorgans of DNA they share with a test subject. Centimorgans are a unit of measurement commonly used in genetics to specify how much DNA two individuals share in common. Larger segments with high centimorgan values typically suggest that two individuals share a recent common ancestor. 

Collaborating with Descendants 

Tom had a close estimated first cousin match who was sharing 836 centimorgans on 36 segments of DNA. Given this amount of shared DNA, there was a 95% probability that this match was indeed Tom’s first cousin. Unfortunately, however, this match had published no family tree or identifying details in connection with their DNA test profile. Even so, using just the unique username of this match, we performed a search on BeenVerified and determined the identity of the match. The match’s BeenVerified profile revealed details of the match’s father, including his birthdate and death date. We were able to use this information in conjunction with other genealogy research websites to extend the match’s family tree, find how he was related to other genetic cousins and identify the likely paternal grandparents of Tom: John S. and Grace L.  

John and Grace were natives of Sicily who migrated to New York around the turn of the twentieth century. After their marriage in 1903, they had fourteen children, including eight sons. One of those sons was the father of Tom’s first cousin match and therefore could not be the father of Tom himself. If he were, then Tom would share much more DNA with his genetic cousin. The seven other sons were each an appropriate age to have been the father of Tom, but the youngest three were less likely given their ages. Additional exploration revealed that two of the older sons were living in the same city as Tom’s mother around the time of Tom’s birth, making them likely paternal candidates.  

While both of these candidates are now deceased, their obituaries revealed they both had living descendants. Using the details reported for these descendants from the obituaries, we located contact information for Michael, a son of one brother, and Carla, a granddaughter of the other brother. Both individuals agreed to test.  

Michael’s Story 

Several months ago, I received a phone call from my cousin Carla. Little did I know that this would turn out to be one of the most important calls of my life. She told me about a call she had from a stranger by the name of Tom. Tom explained to Carla that he was researching his heritage and discovered that the man he knew as “Dad” for seventy years was NOT his father. As with anyone hearing this type of news, Tom was very upset and really needed to know who his real father was and who, if any, the rest of his new family were. 

 At first, I was very upset and skeptical since my father was a prominent surgeon and family man. Could this be one of those scams I had heard all about? Then I thought that if this were me looking for my real father I would hope that someone would be kind enough to help. I was in my early seventies, and after much pondering and prayer I decided to send in my DNA just as Carla had sent in hers.   

Honing In On the Results 

Assuming that Tom was the biological son of one of these brothers, then there were two possible relationship scenarios with Michael and Carla:  

  1. Tom was the half brother of Michael and a first cousin once removed to Carla; or 
  2. Tom was a half uncle of Carla and a first cousin of Michael.  

Carla’s test results were the first to complete processing, and they revealed that she shared 838 centimorgans of DNA with Tom. At that amount of sharing, there was a 96% probability that she was a half niece and only a 4% probability that she was a first cousin once removed. If these were the only test results that we had obtained, then we might have concluded that Tom was most likely the biological son of Carla’s grandfather. However, when Michael’s DNA test results completed processing, they left no room for that possibility.  

Michael shared 1987 cM of DNA with Tom. This amount of shared DNA is only possible for half sibling, uncle/nephew and grandparent/grandchild relationships. It has never been observed between two first cousins, though it is possible for double first cousins. In this case, Carla’s grandfather and Michael’s father married unrelated individuals and share an appropriate amount of DNA with each other to be first cousins once removed, ruling out the double first cousin possibility. Even though Carla’s test results alone suggested she was more likely a half niece, they still left open the small possibility of a first cousin once removed relationship. Meanwhile, Michael’s test results clearly suggested a half sibling relationship and left no room for a possible first cousin relationship. Therefore, we concluded that Tom was the half brother of Michael and a first cousin once removed to Carla.   

“I Have a Brother!” 

When my cousin Carla’s test results came back, it verified that she was a first cousin match to Tom. When I received my DNA results, it left no doubt…my DNA came back 100% proof that I had a brother Tom!

How did this happen? Tom and I started calling each other to try and find the connection between his mother and my father. Where did they live? What did his dad do? What was his mom like, etc.? We discovered that his mom and my mom were very social, usually the center of attraction at parties, loved to dance and drink, and both were very attractive. Then Tom said his dad was in charge of the Convention Center in Atlantic City, NJ. BINGO!!!!!   

My Uncle Lou was the World Bantam Weight Champion in the late 1930s and early 1940s. If you were having a championship title defense in boxing on the East Coast, it would be held either in Madison Square Garden in NYC or at the Convention Center in Atlantic City, NJ. My dad always went to his brother Lou’s championship fights. The world champion always sat at the dinner table with the big bosses of the convention center. So now we had the connection! THIS WAS REAL! 

I sent Tom many photos of our dad and our family. We also described ourselves to each other. We have very similar likes and dislikes, same sense of humor, and the same religious and political views. Tom is larger than me and we don’t look that much alike other than the same nose and I’m better looking LOL. While sifting through photos, I came across our dad’s wedding picture that included his parents and siblings. There was an uncanny resemblance between Tom and our grandfather. I sent the photo to Tom’s phone, called him and asked him to put his phone on speaker, go stand in front of a mirror, and zoom in on our grandfather in the center of the photo. When he did so, I heard Tom say, “Oh my God. I have found my family.” At that moment, two septuagenarian brothers broke down into tears. 

a surprising ethnicity estimate lead Tom to explore the possibility that the father who raised him was not his biological father.

A Cautionary Tale 

This case demonstrates the importance of not discounting possible relationship levels just because they are less likely. Carla’s results suggested she was more likely to be a half niece, but in fact, she and Tom are among the 4% of the population sharing this amount of DNA who are first cousins once removed. Though researchers might be in the habit of dismissing these lower possibilities, some relationships do fall in those ranges of possibility, and someone makes up the 4%. Therefore, before assuming that a relationship is proven, we recommend exercising caution and getting as close to 100% probability as possible.  

Through DNA testing, analysis of genetic cousins, contact with testing candidates and targeted testing of close relatives, we were able to determine the identity of Tom’s biological father. 

Do you have a genetic genealogy mystery you would like help resolving? Contact Legacy Tree Genealogists today. Our team is experienced at utilizing DNA evidence from all major testing companies in combination with thorough records research to break down the brick walls in your family tree. 

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The Journey of DNA’s Inheritance Paths: mtDNA and Y-DNA

DNA has taken a far-ranging journey from our ancestors of long ago. The stories in this article demonstrate how mtDNA and Y-DNA can be used to solve research problems based on DNA inheritance patterns.

*This article originally appeared in NGS Magazine, and is reprinted with permission.

Each human has DNA, a biological code that affects many physical, emotional, and behavioral characteristics. Humans inherit copies of DNA from their parents, who in turn inherited portions of DNA from their parents, grandparents, and other ancestors.

The journey that DNA takes from ancestor to descendants, from generation to generation over hundreds of years, follows four major DNA inheritance paths. DNA testing and consideration of these patterns enable researchers to uncover information about their biological heritage. Two inheritance paths, mitochondrial DNA and Y-DNA, are discussed in this article.

The nature of genetic inheritance can sometimes make DNA even more valuable for genealogical research than documents dealing with inheritance. Genetic inheritance is:

  • Universal—children cannot be excluded from their genetic legacy like they might be excluded from a will.
  • Uniform—with genetic inheritance, no child inherits more DNA than other children.
  • Independent—the fact that one child inherits a part of the DNA does not exclude another child from inheriting a copy of the same DNA.
  • Mutual—descendants share copies of the DNA they inherit from their ancestors.

DNA is like a family photo album containing pictures of many of an individual’s ancestors. Those photos may be copied from other historical family photo collections. Each photo has its original story, and the path that the photo or photocopy took to arrive in the final collection is a story in itself.

Mitochondrial DNA

Mitochondrial DNA is a small, circular genome in the mitochondria (energy power houses) of the cell. It is the only DNA found outside the nucleus. Both males and females inherit mitochondrial DNA from their mothers, but only females pass it on to their children.

Mitochondrial DNA is inherited along the direct maternal line of ancestry.

Since mitochondrial DNA represents an individual’s direct-line maternal ancestry, it can be used to address questions of shared maternal ancestry. Occasionally, mutations are introduced into mitochondrial DNA before it is passed on to a subsequent generation, which can help delineate unique and distinguishable mitochondrial lineages. These lineages are grouped according to their common hierarchical mutations into haplogroups, some geographically or ethnically specific.

When two individuals share the same mitochondrial DNA signature, they share a common direct-line maternal ancestress.

The legacy of an ancestress with no name

In 1718, an enslaved woman from western Madagascar embarked on the slave ship Prince Eugene along with 490 other enslaved individuals.[1] The mitochondria of her cells carried a unique DNA signature found only among natives of Madagascar. Over the next four to six months, she and her fellow slave passengers endured the horrors of the middle passage, and 152 slaves perished.

“Stowage of the British slave ship Brookes under the regulated slave trade act of 1788.” This diagram of a slave ship shows the horrendous living conditions of slaves during the infamous middle passage from Africa to the New World. Wikimedia Commons (https://commons. wikimedia.org).

Upon arrival in Virginia in 1719, she was sold to one of the plantations in the area of York River and renamed by her master with a Christian name. Though her original name was lost, her mitochondrial DNA was passed on to her descendants. Over the ensuing years, she bore several sons and daughters—some by enslaved men on the plantation, some by her master or his overseers. While each of her children inherited her mitochondrial DNA, only her daughters continued to pass on her mitochondrial DNA legacy.

Over the next 150 years, her daughters, granddaughters, and their descendants were bought, sold, and traded between slave-owning families. They were inherited by the children and wives of their masters. Some traveled with their masters’ families to other areas of Virginia and the American South. The name of the enslaved woman was forgotten, but her mitochondrial DNA continued to pass on to her daughters’ daughters’ daughters’ children and grandchildren.

Some of them fled and escaped to freedom in the north. Others labored under plantation slavery. Throughout the Civil War, emancipation, Jim Crow, and segregation, the mitochondrial DNA of the enslaved woman continued to pass down from daughter to children, as a silent witness of the discrimination and pain she and her posterity endured. Her many descendants spread all over the United States.

Several descendants of the enslaved woman have taken DNA tests. Their mitochondrial DNA shows that they share direct maternal roots with each other and with individuals in Madagascar as well as other individuals from the Malagasy diaspora across the globe. All of them carry mitochondrial DNA signatures traced to natives of Madagascar. These signatures are distantly related to seafaring Melanesian populations who began arriving in Madagascar as early as 200 BCE.

While the name of the enslaved woman may be forever lost, the DNA of her descendants hints at a compelling story of her life and the fate of her posterity.

Key concepts

The concepts for incorporating mitochondrial DNA evidence shown in this story include:

  • Mitochondrial DNA can reveal information about unique ethnic origins.
  • The inheritance pattern of mitochondrial DNA means that it can be used to address questions of very deep ancestry.
  • Although only females pass on mtDNA to their descendants, both males and females have mitochondrial DNA.
  • While mtDNA evidence may be able to demonstrate a direct-line maternal relationship, it may not always be possible to identify the common ancestors of two genetic cousins.
  • Mitochondrial DNA can be utilized to explore broad migration patterns and population history.

Y-DNA

Other DNA is found in each nucleus of the trillions of cells in a human body. This DNA is organized into twenty-three pairs of chromosomes: one set of twenty-three chromosomes inherited from the father and the other twenty-three chromosomes from the mother. One of these chromosome pairs constitutes a person’s sex chromosomes. A biologically male individual inherits a Y-chromosome from his father and an X-chromosome from his mother. His father inherited a copy of the same Y-chromosome from his father, who inherited it from his father, in an unbroken line of direct paternal inheritance.

Y-DNA is inherited along the direct paternal line of ancestry. Legacy Tree Genealogists.

Since Y-DNA represents a male’s direct-line paternal ancestry, it can be used to address questions of shared paternal ancestry. This inheritance pattern many cultures and can be used to confirm proposed direct paternal lineages or uncover cases of misattributed parentage. As with mitochondrial DNA, occasional mutations in Y-DNA signatures result in different haplogroups, some geographically or ethnically specific.

When two individuals share Y-DNA, they share a common direct-line paternal ancestor.

Y-DNA inheritance patterns tell the story documents can miss

In the 1730s, two brothers migrated from the Palatinate (in modern-day Germany) to the British colonies in North America. They eventually settled in Berks County, Pennsylvania, on adjacent farms.[2] They both carried the same surname, attended the same church, spoke the same language, and maintained the same customs and traditions. They also carried the same Y-DNA they had inherited from their father and paternal grandfather.

Though they passed some of their traditions down to their children and grandchildren, within a few generations many of their descendants had begun to learn English and join a wide range of other churches, and they gradually lost touch with their cultural heritage. Nevertheless, a biological record of their heritage continued to pass down through multiple generations of descendants. Each brother passed on Y-DNA to each of his sons, who in turn passed on the same Y-DNA to his sons.

After the Revolution, Loyalist descendants fled to Canada, while descendants of neutral and pacifist relatives remained in Pennsylvania. Patriot descendants spread throughout the United States. Some traveled to Ohio and Indiana. Others struck south into Virginia and Kentucky. Yet others migrated to the American West.

Emanuel Leutze, “Washington Crossing the Delaware,” 1851. At least one descendant of these two brothers is reported to have crossed the Delaware with Washington, carrying with him the same Y-DNA brought to the American colonies by his forefather. Metropolitan Museum of Art, New York, NY (https://www.metmuseum.org)

All the while, the sons of the sons of the sons of these two brothers continued to pass on their Y-chromosomes and carry that DNA with them to new localities. Although many of the direct paternal descendants of these brothers carried the same German surname, others did not. One descendant was a pioneer settler of Bosque County, Texas. He never married and had no documented children. One of his neighbors was Mrs. Buckley.

Many descendants of these two brothers have taken Y-DNA tests, and most share DNA with each other. Some who carry the same surname do not match the Y-DNA of other descendants due to unexpected cases of misattributed parentage: undocumented adoptions, extra-marital relationships, children born to single mothers, and other situations.

An individual with the Buckley surname shares DNA with all of the test-takers who are biological descendants of the two brothers. He is a descendant of Mrs. Buckley of Bosque County, Texas. His DNA compared to other descendants of the brothers hints at a story not apparent in the documentary evidence alone.

Key concepts

The concepts for incorporating Y-DNA evidence shown in this story include:

  • Y-DNA can be used to explore relationships between direct-line paternal relatives.
  • The inheritance patterns of Y-DNA make it ideal for exploring and answering questions for more distant generations.
  • Y-DNA often follows the same inheritance patterns as surnames.
  • To guard against the possibility of misattributed parentage, test multiple descendants of a single individual from unique descent lines (through different sons) to confirm that they indeed share a direct-line paternal ancestor.
  • Y-DNA evidence (in fact all DNA evidence) must be considered within the context of available documentary evidence.

Understanding DNA Inheritance Patterns

Consideration of the historic journey that Y-DNA or mitochondrial DNA follows from ancestors through multiple generations to the present day can offer insights into the meaning of DNA shared with other testers and aid in solving genealogical mysteries. The universal, uniform, independent, and mutual nature of genetic inheritance makes these genetic journeys useful for tracing corresponding genealogical journeys. X-DNA and autosomal DNA can also be useful for these purposes, and will be covered in a future article.

Do you have a genetic genealogy mystery you would like help resolving? Contact Legacy Tree Genealogists today. Our team is experienced at utilizing DNA evidence from all major testing companies in combination with thorough records research to break down the brick walls in your family tree. 

1. While this scenario is hypothetical, it is based on real experiences as described in the following sources: David Eltis, Slave Voyages, “Trans-Atlantic Slave Trade – Database,” Prince Eugene, 1719, voyage ID 16224 (https://www.slavevoyages.org/voyage/database); Henry Louis Gates Jr., “How Did My Enslaved Kin Get to Va. From Madagascar?” The Root (https://www.theroot.com/how-did-my-enslaved-kin-get-to-va-from-madagascar-1790861807); The DNA Detectives, “Malagasy ancestral origins Ben Jealous segment,” Vimeo, (https://vimeo.com/109620391); Teresa Vega, “The DNA Trail from Madagascar to Virginia Parts I-III,” Radiant Roots, Boricua Branches, 2015-2017 (http://radiantrootsboricuabranches.com/category/malagasy-slaves-in- virginia). Special thanks to Teresa Vega for her input on the development of this scenario.

2. While this scenario is based on real experiences, the names, locations, and details have been changed to protect the identities of participants.

 

The stories in this article demonstrate how mtDNA and Y-DNA can be used to solve research problems based on DNA inheritance patterns.