While DNA testing and genetic evidence are certainly useful for breaking down challenging historic brick walls, the implications of DNA testing can also hit closer to home in the modern era when it comes to research on misattributed parentage.
In cases of adoption, unknown parentage or misattributed parentage, genetic genealogy methodologies enable identification of close biological ancestors whose identities might otherwise remain unknown, and which represent immediate brick walls for any genealogist dealing with such a scenario in their immediate family tree.
In this series of blog posts, we explore tips for successful genetic genealogy searches dealing with adoption research, unknown parentage, or misattributed parentage.
(Portions of this article are reprinted with permission from the April-June 2022 issue of NGS Magazine )
Genetic genealogy can (and often does) reveal surprise cases of misattributed parentage in test takers’ family trees. Misattributed parentage or ancestry, where a presumed parent is not the biological parent of an individual or their ancestor, is quite common. Rates of misattributed paternity are estimated to be between 2% and 12% and may vary between populations.1 These rates are based on studies of populations during the 20th and 21st century and may not necessarily be representative of historic rates of misattributed parentage. Even so, exploration of what the low end of this range of rates might mean for an individual’s genealogy is informative.
Even with a conservative estimate of 2% probability of a misattributed parentage event per generational linkage, this suggests that approximately 13% of individuals in the general population will have at least one case of misattributed parentage in the first three generations of their family tree (for themselves, a parent, or a grandparent).
Under even more conservative estimates (.5% probability of a misattributed parentage even per generational linkage), most people will have at least one case of misattributed parentage in the first eight generations of their family tree (up to the sixth great grandparent level). Based on this, even if you can document your family tree several generations, it is still a good idea to verify that those documented relationships reflect biological reality using genetic genealogy.
Genetic genealogy test results often provide the initial clues to uncover a misattributed parentage event. These events may even go undetected unless DNA test results are analyzed carefully.
Once a case of misattributed parentage has been detected and confirmed, genetic genealogy can also aid in determining the identity of a biological parent, either for you or one of your ancestors.
Following are some of the telltale signs or clues that you may have a case of misattributed parentage in your family tree, along with some tips of what to do next to determine the identities of biological ancestors.
Clue #1 Unexpected Ethnicity Results
The first clue that you or a close ancestor may have had misattributed parentage could be anomalous ethnicity admixture estimates at one of the major DNA testing companies.
Each company analyzes thousands of DNA markers and determines which combinations of those markers are most likely found in regions around the world. As such they can estimate where some of your recent ancestors lived or came from. Increasingly, companies are not only offering broad ethnicity estimates for larger regions (where ancestors may have lived in the last several hundred to thousand years) but they are also supplementing these reports with specific regions, groups, or migration patterns where a test taker’s ancestors likely lived in the last few hundred years. For more information on how this works, see our article on ethnicity admixture estimates.
Small amounts of ethnicity admixture from populations near to where your ancestors lived are common and even expected, but if you have significant percentages (higher than 5-10%) of ethnicity admixture from unexpected regions and you also have genetic connections to unexpected communities, groups or migration groups, this could suggest misattributed parentage somewhere in your tree.
The size of the unexpected percentage might help you estimate where the misattributed parentage occurred. For example, if your documented family tree is entirely British and you find surprise Jewish admixture, 50% might suggest that you have misattributed parentage, 25% might suggest that one of your parents has misattributed parentage, and 12% might suggest that one of your grandparents has misattributed parentage.
Before assuming anomalous ethnicity admixture estimate means misattributed parentage, test at a few major DNA testing companies. Each company maintains its own reference panel, and analytical algorithms for estimating ethnicity. By testing at multiple companies and paying attention to the overarching patterns, it is possible to get a better and more accurate idea of your ethnic origins. If the anomalous result persists across multiple companies, explore the possibility of misattributed ancestry further. Learn how to create your DNA Testing Plan.
Clue #2 Y-DNA Testing Anomalies
Another sign that you might have misattributed parentage at some point in your family tree is if Y-DNA testing uncovers anomalous connections or a lack of connections to expected family members.
When males perform Y-DNA testing at Family Tree DNA, they can sometimes connect with other males who are related along their direct patriline. Sometimes these individuals are close relatives, related within a genealogical timeframe. Other times, these Y-DNA matches are distant relatives whose common ancestors lived before the advent of heritable surnames.
If you take a Y-DNA test and find no Y-DNA matches, it may be that other direct paternal relatives have not yet performed DNA testing.
If you believe other direct paternal relatives have performed DNA testing and you are not matching them, it could indicate that you or they have misattributed parentage somewhere along the direct paternal line.
If you have Y-DNA matches to many individuals with a different shared surname this could mean any of the following:
- You could have misattributed parentage on your direct paternal line.
- It may be that those relatives are descended from a common ancestor who had misattributed parentage or unknown parentage from direct paternal ancestors with a different surname.
- And/or perhaps direct paternal relatives from your distant paternal ancestors have not yet performed DNA testing.
If you have Y-DNA test result anomalies, consider target testing known relatives who also descend from your proposed direct paternal ancestors. This can help you pinpoint the generation in which a case of misattributed parentage might have occurred. It can also help you determine if there is a case of misattributed parentage along your direct paternal line or if there might be other explanations for your lack of Y-DNA matches, or unexpected Y-DNA matches.
Clue #3 No shared DNA with close relatives who have also tested
A lack of shared DNA with a close relative who you know (or who you believe) also performed DNA testing can also be a sign of misattributed parentage or ancestry (either for you, or your known relative).
All relatives within the range of second cousins should share at least some DNA with each other. If a known sibling, first cousin, or second cousin has performed DNA testing and is not showing in your match list then ensure that the following are true:
- The relative did indeed take and submit the DNA test.
- The relative performed DNA testing at the same company where you also tested (companies maintain separate databases, so if a known cousin tests with a different company they will not appear as a match).
- The relative has opted into DNA matching (some companies offer the option of performing an autosomal DNA test to obtain ethnicity estimates or other reports, but permit opting out of DNA matching).
- The relative’s test results have completed processing (sometimes there is a delay in a cousin showing up in the match lists of others if their test results have just recently completed processing).
- The relative is not using an alias or unidentifiable username (sometimes the cousin may be in your match list, but under a username that you do not recognize).
If all the above is true, then there may be a case of misattributed parentage for you or for your known relative. To determine which individual does not descend from the proposed common ancestors, consider the matches in each individual’s genetic test results.
Example Cousin Scenario 1 and 2
Imagine that you took a DNA test along with your paternal first cousin, Sharon. You are both proposed grandchildren of Paul and Helen Smith. When the test results complete processing, you find that you do not share DNA with Sharon. In this situation there are two main possible scenarios. Either you are not a descendant of Paul and Helen Smith (scenario 1), or Sharon is not a descendant of Paul and Helen Smith (scenario 2).
- If you share DNA with other descendants or collateral relatives of Paul and Helen Smith, while Sharon does not, you can conclude that Sharon is not a biological descendant of Paul and Helen (scenario 1).
- If Sharon shares DNA with descendants or collateral relatives of Paul and Helen which you do not match, then you are not a biological descendant of Paul and Helen (scenario 2).
In this case, it is also possible that neither of you descends from Paul and Helen or that one of you descends from the couple but there are no other tested descendants or collateral relatives. Those scenarios would require additional analysis and exploration.
Scenario 1: You do not share DNA with your proposed paternal first cousin, Sharon (red). You do share DNA with other documented first cousins and collateral relatives of your grandparents at appropriate levels (green) while Sharon does not. In this case, you can conclude that Sharon is not the biological granddaughter of Paul and Helen Smith. Either she is not the biological daughter of Susan, or Susan is not the biological daughter of Paul and Helen Smith.
Note that lack of shared DNA between known relatives strongly indicates a case of misattributed parentage for individuals who are expected to be related within the range of close family to second cousins. More distant relatives in the range of second cousins once removed to more distant relatives may have simply inherited different portions of their shared ancestors’ DNA and may not share DNA with each other.
To determine if this is the case for more distant known relatives, determine if you and your matches share DNA with other descendants or collateral relatives of the proposed common ancestors.
Clue #4 Lower than expected amounts of shared DNA with a known relative
Sharing significantly less DNA with a known relative than expected is another sign of possible misattributed parentage. If your known relative shares half the amount of DNA than would be expected given their proposed relationship, it may be that they are a half rather than a full relative.
To evaluate this possibility, utilize the evaluation tools through DNA Painter and the Shared cM Project to evaluate the amount of shared DNA.2
On the one hand, just because a proposed relationship is possible does not necessarily mean that it is likely. If a known relative is sharing a low amount of DNA explore the possibility of a half relationship.
On the other hand, some relatives just happen to share low amounts of DNA, and although there may be a small probability of a proposed relationship, someone must make up the 5% probability for specific relationship levels.
To determine if your known relative is a half-relative or to determine if they are just a low sharing full relative, explore the matches shared between you and them to determine if shared cousins include collateral relatives of both of your proposed common ancestors or only one of them.
Example Cousin Scenario 3, 4, 5
Imagine a different situation where you and your first cousin, Sharon, both perform DNA testing at the same testing company. When the results complete processing, you are found to share just 550 centimorgans with each other.
According to DNA Painter’s Shared cM Project 4.0 tool, this amount of shared DNA is much more likely between half first cousins (about 80-90% probability) than it is between full first cousins (about 10-20% probability).
In this situation there are three main possible scenarios:
- You are a descendant of Paul and Helen Smith while Sharon is a descendant of only Paul or Helen (scenario 3)
- Sharon is a descendant of Paul and Helen Smith while you are a descendant of only Paul or Helen (scenario 4)
- Both of you are descendants of Paul and Helen but happen to share a low amount of DNA with each other given your proposed relationship (scenario 5).
If you have genetic cousins who are related through the ancestry of both Paul and Helen, while Sharon only has genetic cousins who are related through Helen and shares consistently low amounts of DNA with other descendants of Paul and Helen then you can conclude Sharon’s parent was not the biological child of Paul but was the child of Helen (scenario 3).
If Sharon has genetic cousins who are related through the ancestry of both Paul and Helen, while you only have genetic cousins who are related through Helen and you share consistently low amounts of DNA with other descendants of Paul and Helen, then you can conclude that your parent was not a biological child of Paul but was the biological child of Helen (scenario 4).
If both you and Sharon have genetic cousins who are related through the ancestry of both Paul and Helen, then you can conclude that you and Sharon are full first cousins but simply share low amounts of DNA given your proposed relationship (scenario 5).
Scenario 4: You share 550 cM of DNA with your paternal first cousin Sharon – an amount of DNA more typical of half first cousin relationships (orange). You share consistently low amounts of DNA with other descendants of Paul and Helen (orange) while Sharon shared appropriate amounts of DNA with the same individuals. Both you and Sharon share DNA with collateral relatives of your grandmother, Helen (green). While Sharon shares DNA with collateral relatives of Paul, you do not (red). In this case, you can conclude that your father, David, was not the biological son of Paul.
Clue #5 Close unknown genetic cousins
Another hallmark of cases of misattributed parentage is the presence of close genetic cousins (those sharing more than 200 cM) for whom no known or documented relationship can be determined in the context of your documented family tree or their documented family tree.
To determine whether you or your match have a case of misattributed parentage in your respective family trees, it is useful in these cases to consider the matches shared between you and the match to determine which family tree those shared matches support.
Example Cousin Scenario 6, 7
Imagine that you have a close genetic cousin, Mary, sharing 600 cM who has an extensive six-generation family tree associated with her test results. Based on the amount of DNA you share with each other; Mary should be related in the range of a first cousin to first cousin once removed.
- You could have a case of misattributed parentage in your family tree and may biologically descend from Mary’s ancestors (scenario 6).
- Mary could have a case of misattributed parentage in her family tree and could biologically descend from your ancestors (scenario 7).
- Alternatively, you could both have cases of misattributed parentage in your trees and may descend from a shared common ancestor that is unknown to either of you (scenario 8).
If your shared matches to Mary are known descendants and collateral relatives of your paternal grandparents, Paul and/or Helen Smith, then we can conclude that Mary is also descended from Paul and/or Helen or one of their collateral relatives and that she has a case of misattributed parentage in her family tree (scenario 6).
Meanwhile, if your shared matches with Mary are all descended from a set of Mary’s second great grandparents, this would indicate that you are also descended from this same couple and that you have a case of misattributed parentage in your family tree (scenario 7).
If all shared matches between you and Mary do not have clear relationships to your respective proposed family trees, but instead form their own cluster of known relatives from a completely different couple, then it may be that both you and Mary have cases of misattributed parentage in your family trees (scenario 8).
Scenario 6: You have a close mystery genetic cousin, Mary, who has an extensive family tree associated with her test results, but no documented shared ancestors (yellow). You share 600 cM of DNA with each other which is typical of a first cousin, or first cousin once removed level of relationship. Mary shares DNA with other descendants and collateral relatives of both Paul and Helen Smith. In this case, you can conclude that Mary is also a descendant of Paul and Helen and has a case of misattributed parentage in recent generations of her family tree.
Clue #6 No genetic connections to a particular branch of your family
One additional clue that can signal a case of misattributed parentage is when your match list lacks representation of collateral relatives through a proposed ancestral line.
However, you should exercise caution in these situations to avoid jumping to a hasty conclusion. In this case, absence of evidence is not necessarily evidence of absence. Just because there are no matches from a particular line does not necessarily mean that you are not biologically descended from that family. Consider the following reasons there may be no genetic connections to a particular branch of your family.
- Unrepresented family lines might be composed of several generations of small families that only had one or two children resulting in few living descendants to test in the first place.
- Underrepresented families might be composed of recent immigrants from countries, regions and populations which are not well sampled in the database.
- In other cases, family members from that line may not have performed DNA testing yet.
In these situations, it is useful to consider the family sizes, geographic origins, and other family details for the ancestral line that is missing in your test results.
If a lack of representation from a particular line accompanies one of the scenarios discussed above (no relationship to a known tested relative, lower than expected amounts of shared DNA with known relatives, or multiple genetic cousins with a documented relationship to each other but not to the test subject), then a case of misattributed parentage is likely.
Even so, the best way to explore the anomaly of missing representation is to target test relatives from that family line in order to test the hypothesis that the lack of matches is due to misattributed parentage at some point along that ancestral line rather than low testing representation from that family in the database.
Imagine that in your case, you have many matches who are related through the ancestry of your maternal grandparents, as well as many matches through the ancestry of your paternal grandmother, but you cannot identify any matches who are related through the ancestry of your paternal grandfather Paul Smith.
If Paul Smith was from a family of ten children and descended from a long line of large families in Colonial America, we might expect there to be at least some matches through this proposed ancestral line. Meanwhile, if Paul was the only child of an only child of an only child and was an immigrant from Germany (where DNA testing is not as prevalent), then the lack of genetic cousins from that ancestral line is more likely due to small family sizes and recent immigration from an underrepresented population in the testing databases.
In either case, targeted testing of a documented relative could help confirm or refute the possibility of a case of misattributed parentage.
While none of these signs in isolation or combination are proof of a case of misattributed parentage, if your test results fit one or more of these descriptions, it may be wise to at least consider the possibility of misattributed parentages somewhere in your family tree.
If you come across DNA test results that are anomalous because of ethnicity admixture, Y-DNA anomalies, lack of matching to known relatives, low amounts of shared DNA with known relatives, close genetic relationships to unknown relatives, or a lack of genetic connections to relatives from a particular branch in your family tree, use the tips in this article to pinpoint where a case of misattributed parentage may have occurred and then determine who your biological ancestors were.
If you need help, or even just want someone to review your work to make sure that you are correct in your conclusions, hire a professional genealogist at Legacy Tree to help you explore your biological heritage.
Jane Schwendinger says
Thanks for an outstanding article and the analysis it contains. I assisted five individuals in finding a bio parent. Only one learned of the problem through unexpected ethnicity. The others knew or expected they were not living with their bio parent. I will share this article tomorrow when we all get together to share their journeys..
Anne Marie Vivienne says
Hi, Jane! We’re so glad the article was relevant for you. Thank you for sharing it with your circle. It’s life-changing information for sure!
Richard Hallick says
You have used a conservative estimate of 2% misattributed paternity in your introductory comments, which is probably fair. However most of the data supporting this number only exist for 20th Century families. We should be cautious about extrapolating this number back 8 generations as you have done, because there is no good data set to support the conclusion.
Jim Ensinger says
For years I dismissed Clue #4 for a particular cousin whose degree of match was about half of what it should have been based on the “known” relationship. Cousin matches are highly variable and our match was at the extreme end of the range, probably in the 99th percentile. But I should have seen a clue which is in addition to the clues listed above. Our proposed common ancestors supposedly had a child about two years before they were married. This child had the family name and was listed in the census as a son and I always assumed that it was the child of both of our “known” common ancestors.
This cousin died recently and I was reviewing her file. I came across an obituary that I had not seen before which referred to one of our common ancestor’s stepbrothers. Obituaries often contain errors but that prompted me to look at our shared matches and I found that our close matches were on both of the proposed common ancestors but that as the degree of match became more distant, the matches were only through the relatives of one of our proposed common ancestors. Apparently, our female true common ancestor had a child with an unknown male and this child was subsequently brought into the family as the child of both parents.
Unfortunately, my cousin’s DNA matches are not available to me so I have no idea of the identity of the unknown male. The death certificate for the son (the one born before the marriage of our common ancestors) was filled out by a neighbor and is not at all informative.