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Caution: Invisible Fathers and Autosomal Matching – Who’s Hiding in Your DNA?

Roberta Estes

caution Y

Using autosomal DNA matching alone, NPEs (nonparental events,) also known as misattributed paternity or parentage (MPEs,) undocumented adoptions, and sometimes other terms, often goes completely undetected, especially a few generations back in time.

Generally, this phenomenon occurs when the believed father is not the biological father – for a variety of reasons. Using autosomal DNA alone, especially more than a couple of generations back in time, these situations often go undetected because we are lulled into complacency thinking we have proof via DNA matching, but we don’t.

Let’s look at a real life example of how I discovered and unraveled one of these mysteries.

What We Thought Happened

In the Doe family, two male Doe men were found together in King and Queen County Virginia during the Revolutionary War era. They moved together to Halifax County after the war. They lived very near one another and witnessed documents for each other, lifelong. They were known within the family to be related.

Thomas was older than Marcus, but not enough older for Marcus to have been his son.

Eventually Thomas wrote a will that Marcus witnessed, but Marcus was not mentioned in the will. Typically, unless facing imminent death and the dying person created a spur of the moment verbal will in the presence of whoever happened to be in the room, called a noncupative will, family members who benefited from the will did not witness the document. In probate records, noncupative wills were stated as being such – and Thomas Doe’s wasn’t.

Enter the age of DNA testing. Many of Marcus’s and Thomas’s descendants match each other autosomally, distantly of course, as would be expected.

Everything was just hunky-dory until a Y DNA test of Marcus’s patrilineal descendant (male tester Doe) and Thomas’s patrilineal descendant (son Doe tester 2) proved conclusively that the Y line DNA was NOT the same in those two branches of the family.

Furthermore, Alexander Doe actually had another son, James, whose sons’ descendants Y DNA match those of Thomas, so the Thomas/James Y DNA proved the Y DNA of Alexander, leaving Marcus out in the cold. Furthermore, James was near Marcus’s age, so he could not have been the father of Marcus.

Clearly, Marcus, Thomas and James were related, because the autosomal DNA of their descendants matches and triangulates.

What gives?

What Really Happened

When Alexander Doe died, with a will, his eldest son, Thomas was made the guardian of his three underage daughters. One married a few years later, but the rest of the daughters disappear into the mists of time.

Adding to the confusion, the King and Queen County, Virginia, records burned, destroying what evidence might have existed. Fortunately, the family lived on the border with Essex County and a few records were filed there.

I’m giving you the answer to the question of what happened now, because I want to discuss how this misattributed parentage went undetected, and why you CAN’T detect it without Y DNA testing.

Marcus wasn’t the son of either Alexander or Thomas, but was the illegitimate son of Susan, daughter of Alexander, when Thomas was her guardian. Susan probably died, because given the nature of how close Thomas and Marcus were, Thomas probably raised Marcus and Susan is never mentioned again.

Of course, the autosomal DNA can match because autosomal DNA does not distinguish between DNA descending from maternal or paternal lines, like Y or mitochondrial DNA, it only looks at matching.

The only way to ever “notice” that Marcus was NOT patrilineally a Doe was to Y DNA test Marcus’s male descendant and a Doe male descending from Thomas Doe or brother James.

Due Diligence

If you’re asking how we know that the break in the Y DNA wasn’t between Marcus and the current male tester in his line, that’s a great question and shows that you’re thinking.

You’d need to Y DNA test a male descended from Marcus through a different son. Of course, in this case, we already have two sons of Alexander whose Y DNA matches so that line is proven.

Why We Can’t Tell Using Autosomal

Let’s look at the original presumed relationship again – the relationship reported in all of the family history documents written in the early 1900s. This is what we believed, of course.

Using the chart I compiled from Blaine Bettinger’s Shared cM project, here, I added the columns above reflecting the relationship between Marcus, Susan and Thomas if they were all children of Alexander. You can see that the various testers today were 6th cousins, or Degree 13 relatives who would be expected to share 21cM of DNA on average. The range of shared DNA for 6th cousins is from 0-86 cM. These cousins all shared in the expected range for this relationship, so no eyebrows were raised.

Looking at the real relationship in the chart above, you can see that the testers are actually “once removed” meaning that one is a generation further down the tree than the other one. This makes them 6th cousins once removed, or Degree 14 relatives who share 16 cM of DNA on average. However, the range of DNA seen at 6C1R is 0-72 cM, still very close to the Degree 13 relationships. The two men in question, as well as the rest of the descendants of Marcus, Thomas and James all match within the expected range for either 6C or 6C1R.

The bottom line is that without Y DNA testing, one can NEVER assume (you know about that word) the line of descent is as presumed, or even as documented in records, even with an identical-by-descent autosomal DNA match. (To read about identical-by-descent versus identical-by-chance, or false matches, click here.)

An autosomal DNA match (at this distance) only shows THAT the two people are related, not HOW they are related.

Records have been known to be incomplete or wrong, intentionally or otherwise. We need combinations of records and multiple kinds of DNA tests.

Y DNA to the Rescue

Without Y DNA testing, Marcus would forever have been believed to be the son of Alexander. Some researchers attributed Marcus as the son of Thomas, because of their close relationship in Halifax County. Now we know that he was unquestionably not the son of either man, and thanks to Y DNA we know the likely candidate surname of his father thanks to multiple high-quality Y DNA matches.

In time, utilizing autosomal+Y DNA combined with genealogical records, we may actually be able to narrow down the candidates for Marcus’s father or at least candidate families. Susan had to be geographically close to Marcus’s father to conceive Marcus, and neighbors are always the best candidates.

Advanced Searching for Combined Matches

Another benefit of Y DNA testing is that Family Tree DNA offers a combined matching tool. From the account of Marcus’s descendant who carries his Y DNA, we can query the system for anyone who matches both the Y DNA and autosomal DNA through the Family Finder test.

Click to see a larger image. Note the selected options.

This technique provides a way to determine who matches on both the Y and autosomal tests. Of course, there’s no guarantee that any two people will match autosomally beyond 2nd cousins. After that, it’s a bit of a crap shoot, and the further back in time, the less likely people are to match. However, you won’t know unless you try. If you do match on both tests, keep in mind that the dual match can also be from two different ancestors.

However, if the Y DNA matches the known patrilineal line, you won’t have to worry about misattributed paternity because you know the patrilineal link is solid (unless of course another male from the same line was involved.) Y DNA can’t tell you who, exactly, just that you match the patrilineal line.

You need the combination of both Y and autosomal DNA.

Which of Your Lines Need to Y DNA Test?

How many of your surname lines are you assuming descend through the direct paternal line when in fact the match could be a result of a sister or female relative giving birth and giving the child her surname?

When illegitimacy is involved, the child takes the mother’s surname but the father’s Y DNA is passed to the male child. The child carries the same approximate amount of autosomal DNA of the grandparents as if the child had been born to the brother in our example, and the family often went to great pains to hide the fact that the birth was illegitimate in the first place. After a generation or two, the ONLY way to know is to Y DNA test.

Who might be hiding in your tree? Which lines do you need to test? Who is available from those lines to test?

You can purchase both the Y DNA and autosomal Family Finder tests at Family Tree DNA. You can order a 37 marker test here which will be enough to see if you match the surname you expect. Be sure to join relevant projects too, especially the surname project. I wrote about how to join a DNA project here and how to determine which projects to join here.

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