Friday, June 30, 2023

The Difficulty With DNA


At the beginning of a research project, I first let my brain take in all the possibilities. There can be a lot to consider when the slate is blank and there are plenty of options to explore. With this upcoming month's project to explore what can be discovered about Johanna Flanagan Lee, cousin to my father-in-law's grandmother, I've started laying out the branches on her direct line, filling in all the descendants. And I can't help but wonder if any of them has thought about taking a DNA test.

Even if one of these descendants of Johanna did decide to take a DNA test, checking the ThruLines tool at is simply not an option in this case. The readout for this tree only goes as far back as Anna Flanagan, my father-in-law's great-grandmother and aunt to Johanna. Even though I've entered a place holder in the tree, labeled simply "Flanagan," for Anna's father—and thus, Johanna's paternal grandfather—there are no other DNA testers in the Ancestry pool to show up as a ThruLines match.

There may be an explanation for this dearth of matches on the Flanagan side. For one thing, the very situation Anna found herself in, directly after the birth of her daughter Catherine, meant Catherine would have no full siblings. Anna's husband, for whatever reason, abruptly needed to leave the country and sail to America, leaving Anna and baby Catherine behind in Ireland. Though Anna herself sailed to Boston in search of him, she never found her husband, and never married again, eventually settling in Chicago with the rest of her immigrating Irish family. Perhaps for that reason, family obituaries included niece Johanna among the survivors of the departed: this simply was such a small family as to leave very few names to mention as bereaved relatives.

Despite this situational reason for lack of Flanagan DNA matches, I realize one thing. Among those in my father-in-law's extended family, I apparently have a line of female descendants which would qualify as the matriline leading back to Anna.

Of course, even if I could find a member of that matriline willing to spring for a mitochondrial DNA test, it wouldn't point me back to the originating Flanagan side of the family, but through Mr. Flanagan's unnamed wife onwards to the roots of her mother. And the matriline for Anna's daughters' daughters would not be the same as that of her niece Johanna, who was related to Anna through her father's line.

Likewise, finding any male Flanagan descendants willing to take a Y-DNA test would only work if I could find a descendant of a brother of Anna. If Johanna had a brother, that would help, but I don't even know that much about Johanna yet. Even if I did know who her brother might have been, a Y-DNA test would only help if that brother had sons, who had sons, who had sons....

As it is, the only DNA that might help in this case would be that plain ol' vanilla version: autosomal DNA, the test which reliably points out all those distant cousins in the family, sometimes even up to as remote a relationship as sixth cousins. For my current volunteer test taker, that would mean a match at the fourth cousin level.

That fourth cousin level is very do-able, except for one small detail: this family has what is sometimes called long generations. In other words, the number of years passing between each generation, in this family's case, stretches close to forty years. If Johanna's generations were shorter than this span in Anna's family, that would leave us looking for matches at the level of once-removed or more distant. Since we are approaching those distant stretches where DNA sometimes drops off the testing radar for viable matches, adding those generations "removed" can push us beyond the detectable thresholds necessary to identify genetic matches.

And so, in this quest to find more about Johanna's family, I'll keep looking for DNA matches. But I won't hold out much hope, considering these difficulties. For Johanna's descendants, it's better to keep a closer eye on the paper trail of genealogical matches than the DNA trail of genetic matches.

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