Monday, August 7, 2023

Depending on D N A


It's a scary world, this realm of genealogy without documentation. After spending a lifetime backing up assertions in the family tree by confirming records, trusting a DNA test result as the sole verification of relationship seems, well, weird. I get the science of it all, but still cling to old research habits. It seems odd to depend on DNA alone.

With the discovery that I might have missed an entire branch of my father-in-law's Tully line, I'm at a loss to find records to confirm the connection. Perhaps that connection has fallen in the gaps between eras of record-keeping diligence. 

Canadian immigrants Dennis Tully and his wife Margaret Hurley produced at least seven children from whom eight descendants match the DNA of another Tully line's descendant. Those children's lines can be easily traced from the 1871 census record of Warwick in Lambton County, in which they were all listed, long after both Dennis and Margaret had left their respective homes back in Ireland.

Going in the reverse direction, however, is not quite so easy. Though Dennis and Margaret were both born in Ireland, they likely married after their separate arrivals in "Canada West"—but where was that marriage record? Worse, though Dennis was supposedly the connection to my father-in-law's Tully line, there was no record of his baptism that could be found back in the family's home in County Tipperary; his 1830 birth apparently pre-dated the available Catholic Church records for the Ballina parish where our Tully family attended.

And yet, there they are: eight results showing a DNA connection to my husband—seven through Ancestry DNA and one at MyHeritage.

There are, of course, some drawbacks to such data. None of the matches represents close cousins, due to the time frame involved. We are talking about the descendants of a man born in 1830. The DNA relationship estimates range from third cousin through third cousin once removed and twice removed. Going by the numbers, that means the closest match is above seventy centiMorgans, but the least of them registered at nine centiMorgans—hardly a reliable number. On inspection, though, each of these matches offers a family tree clearly detailing the line of descent from Dennis and Margaret to their own generation. The only problem is that I have no way to connect that Dennis Tully with my father-in-law's own Tully line.

To say that these DNA matches hover around the level of third cousins—give or take a generation or two—implies an assumption about just where in the Tully family tree this ancestral Dennis belongs. And that is the rub. I'm not entirely sold on where in the tree this Dennis should belong. Granted, it could be quite possible that he was the son of my father-in-law's own ancestor, his great-grandfather who also carried the name Denis Tully. But this younger Dennis could possibly have been a nephew, son of an as-yet unnamed brother of our own Denis.

And yet, to discard these matches out of hand, simply because we can find no adequate recording of family relationships, seems absurd. The DNA is telling us something. We need to delve into the details a bit further to see whether we can get a clearer take on what that message might be.  

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