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Identifying Unknown African American Lineages Using DNA

Roberta Estes

My article asking Ancestry to reconsider purging 6-8 cM matches due to the effects on African American genealogy raised questions about how one could identify a lineage for an African American (or anyone really) who has no knowledge of their tree beyond a certain point in time.

That’s actually a really good question, so let me explain by using examples from my own family that illustrate how the science and matching techniques work together.

African American DNA isn’t any different than other DNA. What is different is that African Americans have absolutely no records, no surname and no context before emancipation in the 1860s and the first census in 1870. Many, and especially new researchers, have no idea where to look and without records, DNA is their only way to make connections back in time.

Unfortunately, this is also the threshold in time where the DNA of ancestors prior to 1870 is now chopped into segments the size of 6-8 cM.

Accidental Discovery

This week, while I was working on evaluating my smaller segment matches at Ancestry, I noticed that one was to an African American man, based on his profile picture, with whom I shared 7 cM.

I clicked on the match and then on Shared Matches. Even though this match is only 7cM, Shared Matches of 20 cM or above will show. The only shared matches that won’t show are shared matches below 20 cM, because they are presumed to be further back in time than 4 generations. I do wish Ancestry would show all shared matches.

We had 12 shared matches, ranging from 20 to 57 cM. some that I had previously identified as descending from the same couple.

I thought I recognized two or three of these people as having tested at other vendors.

I reached out to my match, we’ll call him Frank. He said that his mother, aunt and another relative had all tested at Ancestry too. I told Frank that I didn’t see their names in our Shared Matches, when I realized that could be because I shared less than 20 cM with them.

Sure enough, when I searched for the surname of the testers in question, they are all 4 on my match list.

Based on who we match in common at Ancestry, I *thought* I knew which ancestral couple we share in common. We all only match on one segment, but I can’t tell if it’s the same segment of course without a chromosome brower. And I can’t tell if these people also match each other at Ancestry on a common segment, although I would certainly presume so since he told me that they are closely related.

I asked Frank to transfer their results to either FamilyTreeDNA or MyHeritage, the other two vendors that accept transfers, where we can obtain segment information. Frank and two of his relatives transferred from Ancestry to FamilyTreeDNA where I’ve tested many family members over the years.

When I can identify a common ancestor with a match at any vendor that provides segment information, I paint those segments at DNAPainter.

Indeed, I did match Frank and his family members on the same segment, as do many of my cousins who are confirmed to have descended from a common ancestor.

The graphic below from DNAPainter shows all of my matches to this segment from all vendors identified to the purple couple.

I went to DNAPainter and painted these three smaller segment matches from Frank and his relatives, assigning them to the same ancestral couple. As you can see, they fit right in.

Can you tell which three of the people above are these three new cousins that I matched initially on 7 and 8 cM at Ancestry? No, of course not, because this is the exact same segment where I match all of my other cousins who are all assigned to the purple couple.

Given that these matches shown in purple are all descended from a specific line, my three newly-found cousins match them and must be related to that line in some way.

This match isn’t identical by chance, because their segment phases within their family, through Frank’s mother and another close relative.

We all share the same DNA, it’s phased in Frank’s family through three generations, so the conclusion must be that we share a common ancestor. This is an example of classic triangulation with many proof points.

Frank and his relatives then searched for the surname in question and found more people in their match lists from this same couple. They just didn’t know where to look before, but now they do.

If we accept that shared DNA between all of the purple people who are identified as descendants of the same ancestors share that ancestral couple’s lineage because they share the same DNA segments, and because they all match each other, then we must also accept that our three new cousins share the same genealogical line, because they share the same DNA as the previously proven cousins.

Now, of course, we need to work on geography and proximity, meaning figuring out exactly how our new cousins might descend from this line. We can also work on identifying matches to the wives lines’, if the wives are known, which may help place the most recent common ancestor. It’s also possible that we match because of an ancestor upstream of the purple couple.

In this case, there is no male in our match list that is descended from the appropriate surname line, so Y DNA testing is not an option. They are currently looking to see if they can find a qualifying male to test.

However, in another case, from some months back, we were able to identify an appropriately descended male.

The Smith Case

In this case, Smith is the fictitious biological surname. The tester, we’ll call him Joe, was an African American male who didn’t know who his family was before emancipation.

Joe and I initially discovered several random, mostly relatively small, common autosomal DNA matches that are part of an identified triangulation group. This was enough to identify the family in general and provide us with a working theory about who might have been his ancestor, but we needed more information.

Eventually, Joe found a male that descended from his ancestor who we’ll call Harold, a male emancipated when slavery ended. That man Y DNA tested, and indeed, his Y DNA matches my Smith family paternal line exactly.

Several of my proven Smith ancestor’s known relatives’ autosomal DNA matches the DNA of Harold’s family. Joe asked several family members from various children of Harold to test, and they too match various Smith descendants on many of the exact same segments of DNA.

I don’t match all of Joe’s relatives, but I do match some. On this common smaller segment of 7.7 cM, Joe’s family is painted in green and purple. My oldest progenitor, the Smith Father is painted in blue. Descendant generation matches are painted in other colors. However, since I now know that the blue portion is progenitor Smith, all of these segments can be tracked back to him on that side of the family – along with the segments carried by Joes family members who descend from multiple children of his progenitor. In reality, we now know that all these segments are actually blue – because it’s the exact same DNA.

That’s not all. There’s more evidence.

My Smith ancestor owned a female slave, and there were only two males of the right age that could have impregnated the mother of Harold who was emancipated. His mother had died before emancipation. The male child, Harold, listed as a mulatto was found in the 1870 census living in the household of the widow of father Smith. Did she, or did she not know that Harold was either her deceased husband’s son or her grandson?

In this Smith case, we have several pieces of evidence:

The smaller segment DNA evidence led us here. How much evidence do we need to draw at least a preliminary conclusion that Joe is a cousin? And, given that Joe’s family’s DNA matches the Smith family DNA exactly, and in descendants of multiple children in both lines, what other possible explanation is there? Add to that the Y DNA evidence.

Can I tell Joe whether Harold’s father was the Smith father or the Smith son? If Joe and his family autosomally match the ancestors of the Smith widow, then Joe’s ancestor is (probably) the child of the Smith son. So far, they don’t, so it’s most likely that the Smith father is our common ancestor, not the Smith son.

Joe then added Harold as a child of my Smith ancestor on Ancestry, using Harold’s biological surname, Smith, in an attempt to cause a ThruLine to form. Of course, had Joe used a different surname, one that Harold adopted at emancipation, assuming it was different from Smith, the ThruLine would not have formed. Another challenge for African American researchers or anyone whose biological surname is not the same as their surname used.

When I checked my ThruLines this week, I found three people descended from our common ancestor, Joe plus two more family members that I didn’t know had tested at Ancestry.

These matches are now safely “saved” and won’t disappear when the purge occurs in early August, but the two 6 cM matches would clearly have disappeared otherwise and the 8 cM segment at Ancestry was a 7.7 segment at the other testing company, so it would likely have disappeared too. Ancestry rounds.

Joe’s segment match to me was the key to being able to reconnect our families initially. Without this critical clue, we would never have been able to reunite our family. Yes, we are a family. We’ve met and had a reunion. We’ve shared meals. I am watching his beautiful children grown up. And we would never have found each other without DNA.

All thanks to those segments between 6 and 8 cM that some opine aren’t real and aren’t relevant.

Some matches aren’t relevant which is why we need more evidence than one match, but some are very valid and therein lies the gold.

Those matches are the gateway to research – clues to be evaluated just like any other clue. All evidence must be evaluated, genetic or otherwise.

We don’t discard census records out of hand because they might not be our ancestor without evaluating the evidence presented. DNA matches that stand a 50% chance of being accurate (at 7 cMs) and not false positive shouldn’t be categorically dismissed either.

A starving person doesn’t discard a basket of produce because only half of it is edible. Yet, that’s what’s about to happen.

African American Testing

African Americans who test have a blank slate, with no surnames, to work with before emancipation. Segment matches, and often segments between 6 and 8 cM because the passage of time has whittled them to this size, are the clues that allow African American researchers to begin reassembling their ancestral family.

In many cases, genealogists more fortunate don’t need smaller segment matches to piece together our family puzzles, but those working with little or no information on any line before 1870 need every clue they can get. The rest of us can simply ignore what we don’t want – but they can’t recover something taken from them.

Had it not been for that 8 cM match with Joe (actually 7.7 at the other vendor), I wouldn’t have found those cousins, and I wouldn’t have been able to figure out the line through which we are related. Without my work with known family, it’s very unlikely that Joe and his family would have been able to figure this out with no context. For them, it was a needle in the haystack. For me, I had already identified those ancestors and assigned relevant DNA segments to those ancestors. For me, there were records outside of DNA and DNA only confirmed my genealogy. For them, DNA is all they have – just a genetic  prayer.

These are just two examples of how DNA connections reassemble families for African Americans specifically and other researchers whose more distant family members are unknown.

Please Share

Feel free to share your experiences in the comments.

Please also share this and my original article with your genealogy friends and organizations. This topic is not welcome in some places. We don’t have long, so it’s up to you to spread the word.

Plea to Ancestry – Rethink Match Purge Due to Deleterious Effect on African American Genealogists

I’m still hopeful that Ancestry will reconsider. It benefits them, and us, to do so.

Ancestry’s email is ancestrysupport@ancestry.com and phone is 1-800-958-9124.

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