Sunday, December 28, 2014

The Steep Learning Curve of DNA Testing

If you’ve been an avid genealogy researcher for any amount of time, you’ve no doubt at least wondered about how available DNA tests could boost your research efforts—if not actually tried them, yourself.

For me, living within a six hour drive from a primo genetic genealogy conference—and better yet, only an hour’s drive from one of the founders of ISOGG and one of her annual seminar locations—it’s no problem to avail myself of ample learning opportunities.

Even so, when I had a surprise email visit from someone who announced an exact match to my mtDNA results, I still found it hard to put that head knowledge to use.

The goal, of course, is to take test results for both parties and then examine how we connect on our family trees. That may sound like a relatively straightforward proposition. But it isn’t. At least not for a family like ours. On the one side, there’s the handicap of the closed adoption process—granted, alleviated to a small extent by the capable help and support of the many members of ALMA.

On the other side, there’s that difficult issue of not being able to determine the parents of one of my direct female line—specifically, the Georgia-born Mary who married Thomas Taliaferro Broyles, brother of the Charles Broyles we’ve been learning more about lately. That’s why I’ve been pursuing whatever information I can find on her: unless I uncover more of her identity, she will remain my brick wall ancestor who keeps me and my new mystery cousin match from discovering our ancestral nexus.

You may remember when I first met this mystery cousin online. (If you don’t, you can pick up on that brief story here.) Since then, we’ve both been doing some work, lots of emailing back and forth, and discussing ideas for breaking out of this tight loop. And, thanks to a sale going on at Family Tree DNA, I took a different kind of DNA test, to help us see how closely we might be related.

You see, between us and whatever common female ancestor we both share, we have an exact match—meaning no mutations from that generation down to ours. That could be three or four generations. Or three or four hundred years. Or maybe a thousand years. It’s hard to tell—especially without both parties’ family tree paper trails to assist us.

Even so, there is another way to test for relationships up to the distance of sixth cousin. At Family Tree DNA, that test is dubbed the “Family Finder” test. I took it. And just before Christmas, I got my results back.

Though we were both hoping the results would shed some more light—especially for someone who is an adoptee wishing to discover more about birth parents—but unfortunately, in this case, the test didn’t lead us closer to any truth on our connection. We did not show up as matches—even at sixth cousin to remote level—on each other’s pages at the testing company.

Of course, that doesn’t negate the results from my previous mtDNA test. I firmly believe those still stand. It’s just that our relationship likely is more remote than the level of sixth cousin. And think about it—with my brick wall firmly ensconced at the second great grandmother level, I can’t even begin to document anything beyond the point of third cousins. So either I have to break through my research brick wall, or we need to find a way to examine the data below the seven centiMorgan cutoff level set by the testing company for their listing of matches. (If all this is Greek to you, you may find ISOGG’s explanation of autosomal testing results and their definition of centiMorgans helpful to review.)

While those recent DNA test results proved disappointing for my newly-found adopted cousin and me, the experience called me back to not only review all my own matches, but those of the other family members I had tested as well. It turns out I am finding several other cousin matches between the three individuals whose test results I am currently overseeing.

The process of DNA testing is just that, a process—not just a swab-the-cheek-and-that’s-it approach, but a sequence in which test results are determined, then matched up to other individuals who have also tested. More results get added to the person’s database as more individuals test and show up as matches. From that point, the information does little without our input and follow-through to seek out and confirm known matches, and puzzle over the others indicated.

For the most part, in the past, I couldn’t find any connections. But with perseverance and hard work, bit by bit, I’m seeing some connections and working to confirm relationships. With every connection I find, I also find that nebulous “head knowledge” transformed into a real working knowledge of what is being documented before my eyes. The terms seem to make more sense. The puzzle pieces seem to fit together in a way that I can get my hands on. That head knowledge becomes a working knowledge, and the science begins to work for me.

With each relationship confirmed by both parties in agreement, our feedback helps science hone in more carefully to fine-tune their predictions about genetic matches. This is where citizen scientists and crowdsourcing can once again aid scientific progress. While it means a steep learning curve for those unaccustomed to the statistics—or even the definitions—of the field of genetics, genealogists are demonstrating that we are capable of grasping enough to at least step on the field as players who can make a difference in confirming a body of knowledge for the common good.

Better yet, I’m getting my hands on a way to confirm my genealogical paper trail that I’m learning to make work for me in interesting ways. Hopefully, at some point, that will include helping a mystery cousin find those roots as well.


  1. I don't understand the Family Finder -- how is it different from the yDNA or mtDNA tests?

    1. That's a key question, Wendy, so thanks for bringing that up. Since we're talking about using DNA testing for genealogical purposes, it helps to visualize a family tree chart while discussing this.

      You already know that the Y-DNA test helps reveal the male line--in other words, the father's father's father, and so on back in time on that line which we can visualize as the person marked in the far left spot in each generation's place on the traditional family tree diagram.

      You also know the mtDNA test does, basically, the same for the mother's line: the mother's mother's mother, and so on, back through history. That would be represented, on the traditional family tree diagram, as the person on the far right of each generation.

      The "Family Finder" test (as one company has dubbed it) is the autosomal DNA test. Rather than extrapolate information from either the X or Y chromosome, this test pulls genetic information from the other, numbered, chromosomes--called autosomes.

      While the Y line and the X line can measure far back in time, and rarely mutate, the autosomal DNA test--sometimes labeled as the atDNA test--is not as reliable for what is sometimes called "deep" history. However, it is a somewhat reliable predictor of familial relationships up to the distance of about sixth cousin.

      If you have been visualizing all these tests, using a mental image of a family tree chart, showing you at the bottom of the page, your parents above, with father to the left, mother to the right, and so on, up the generations, you'll realize we've already spoken about the Y line, going up the generations diagonally to the far left. You also have visualized that X line, diagonally trailing backward in time, along the far right of the chart.

      Now, think of everyone in the middle that hasn't been connected by either the Y or the X lines. These are the people like your father's mother. Or your maternal grandfather's cousin.

      Those are all the relatives that can be extrapolated by using comparisons through a chromosome map, once you've taken the autosomal DNA test--or "Family Finder." Not only can the level of relationship be predicted--like second to fourth cousin--but by process of elimination with others in your extended family who have tested, specific family lines may be indicated.

      For instance, since my half-brother already tested, we can compare our results with other potential matches (brought to our attention by the testing company with the customer's permission) to see who else matches on our father's side of our family (our shared parent), from siblings and first cousins, back to about the relationship level of sixth cousin.

      ISOGG--the International Society of Genetic Genealogy--has an informative wiki page that explains it much better, if you would like to check it out here.

  2. Sounds complicated to me, but if it unearths a cousin for you I think it is wonderful! :)

    1. Oh, it will unearth a cousin or three for sure, Far Side!

  3. With all the details encoded in DNA, it's a shame it's so hard to read!

    1. Well, it may require a steep learning curve, just to be able to read it, but I'm determined to learn how!

  4. My name is Erin Lee, father was Edward Flanagan Lee, California connection

    1. Erin, thank you so much for getting in touch! Let's talk further via email.


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