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Verifying Aunt Mom

Reader Linda Bell Pollard has a major mystery in her family history.

“My father, now deceased, was told he was adopted,” Linda writes. “After he passed away, a member of his adoptive family told me that he was adopted, but his biological mother was his adoptive aunt. In other words, his adoptive mother’s sister was his biological mom. So his adoptive mother was his biological aunt. That entire generation and all before them have passed away.”

So, she says,

I want to verify the family rumor is true or false. I have written to just about every agency in NY where his certificate of birth is from and although I’ve paid all their fees, they tell me they have no record of his adoption. I’ve written the adoption agency where this family member who is now deceased told me his adoption took place and they have no record of him. Is having a distant relative take a dna test my only option to prove or disprove the family rumor? It would be nice to connect with his biological family. I am tracing my heritage and it’s a dead end with my dad. Having a family medical history for my daughter would be nice.

DNA testing may not be Linda’s only option but it’s certainly a good place to start since it should be able to tell her fairly quickly if she’s barking up the wrong family tree.

Let’s look at the situation here. The person Linda has available to test in her line is herself. The person whose DNA she inherited and wants to link to others is her father’s, and the people she wants to try to identify are in her grandmother’s line.

YDNA won’t work here since that’s the type of DNA that’s passed from father to son to son in the direct male line,1 and Linda’s interest is in a line that goes from a female (grandmother) to a male (father) to a female (Linda).

Mitochondrial DNA (mtDNA) testing won’t work here either since that’s the type of DNA passed from a mother to all of her children but that only female children then pass on to their children to establish a direct female line.2 Here Linda’s line begins with a female (grandmother) whose mtDNA was passed to a male (father) but that male could not pass it on to his child (Linda). Linda inherited her mtDNA from her mother, not her father.

So the test that Linda can look to in order to provide the answer is the autosomal DNA test. That’s the test that works across genders and helps identify cousins in recent generations.3 What she needs is a descendant of a known and documented ancestor of her suspected aunt-and-mother candidates to test against.

The chart above (click to enlarge) shows one hypothetical family with Linda and her father in blue, her suspected aunt and mother candidates in red and the grandparents of those two women in yellow. If Linda can locate any person willing to test who’d be in one of the green slots, she’d have an excellent chance to determine if the relationship is what she suspects.

If her theory about the adoptive aunt being the biological mother, then anyone in one of the dark green slots would be a perfect candidate to test — such a person in the higher level would be a half-sibling to Linda’s father and the children of such a person would be Linda’s half-first cousins. The chances of achieving a match in an autosomal test at that level are about as close to 100% as you can get because of the amount of DNA they would likely have in common.

But even if that woman had no descendants, or none willing to test, the others in the lighter green still give Linda an excellent chance of a match. Those in the higher level would be second cousins to her father and second cousins once removed to Linda. Those in the lower level would be Linda’s third cousins, if the theory about the adoptive aunt being the biological mother is correct.

At the second cousin level, the odds of a match in an autosomal DNA test are estimated to be about 99%. At the third cousin level, they’re still very good — about 90%.4 It does happen that you will encounter that third cousin who simply doesn’t share enough DNA to be called a match5 so getting as many people to test as possible is always a good idea.

Even at the fourth cousin level — if Linda had to go up another generation to a common ancestor and then back down to a person willing to test — the odds are around 50-50 of getting a match.6 There, getting more people to test may be critical, to avoid the risk of prematurely concluding there isn’t a common ancestor as opposed to simply not enough DNA in common to conclude that there’s a match.

And, of course, a side benefit of autosomal DNA testing in this case is that there’s also a chance of stumbling across evidence of the biological father’s family here as well as evidence of the biological mother’s line if it turns out that it’s not the adoptive aunt. With more and more people doing DNA testing, there’s always the chance that, somewhere down the road, someone you’re not aware of now will test — and prove to be the match that gives you the answer you’re looking for.

Good luck in finding your test candidates, Linda, and in getting the answers you need.


  1. See ISOGG Wiki (, “Y chromosome DNA test,” rev. 27 Apr 2013.
  2. See ISOGG Wiki (, “Mitochondrial DNA test,” rev. 24 May 2013.
  3. See generally Judy G. Russell, “Autosomal DNA testing,” National Genealogical Society Magazine, October-December 2011, 38-43.
  4. Ibid., at 39.
  5. See Judy G. Russell, “Widen the net,” The Legal Genealogist, posted 7 Apr 2013 ( : accessed 25 May 2013).
  6. Russell, “Autosomal DNA testing,” at 39.
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