What Were the Chances? A Tale of DNA

About two and a half years ago, I took an AncestryDNA autosomal DNA test, and linked the results to an Ancestry member tree. I looked over my matches now and then, but practically all of them were in fourth cousin range and beyond, most of them had no tree or only a private one, and few of the ones who did have public trees had any apparent connections to mine. There were a couple of matches around second cousin range and a bare handful at third, but I hadn't gotten around to investigating them further.

Then, a few weeks ago, two new matches, both female, popped up at the very top of my match list – still in 2nd-cousin territory (I have no full first cousins), but the highest yet. The top match (500 cM) was administered by the second match (299 cM), so they looked pretty much like a mother and daughter. And based on one of our shared matches (one of the few which I had been able to identify from their posted tree), the match had to be through my paternal grandfather. Trouble was, the surname was completely unknown to me, and the tree attached to the top match was private.

Even taking into account the possibility of an outlier at the extremes of observed shared DNA ranges, 500 cM is almost certainly in the class that includes first cousins once removed, half-first cousins, great-great-aunts, and half-great-aunts, with a second cousin just barely possible. Anyone at the great-aunt level or older would have been deceased long before atDNA testing began. And, since I have no full first cousins and my grandfather had no siblings who lived to adulthood, I have no (full) first cousins once removed or second cousins on his side.

That leaves half-first cousins. Well, that had potential; before his fifth and final marriage to my grandmother, my grandfather fathered five other children (that I know of) with four different mothers, all before the turn of the 20th century. Thus I had four half-uncles and a half-aunt who could in theory have given me half-first cousins. However, the reality is a bit more restricted in scope:

• Half-aunt Hazel – four sons with children; one daughter, unmarried and childless
• Half-uncle Kenneth – married twice, no children
• Half-uncle Leonard – one adopted son, no biological children
• Half-uncle Chester – no record after birth registration, assumed died as child
• Half-uncle Vinal – died as an infant

In other words, my only known female half-first cousin had no children, male or female – and she died in 1995 and was thus certainly not my 500 cM match! Which left, well, no leads at all.

Unless...

What about half-uncle Chester?

A couple of years ago, I posted some speculations here, entitled Whatever Happened to Chester L. Kirk?, in a 52 Ancestors post. Chester L., the son of my grandfather Chester F. Kirk and Nellie Crosman (who, as it happens, was not one of Chester's five wives), apparently dropped off the face of the earth after his birth was registered. No death record, no census records, no marriage record... he just disappeared. It seemed likely he had died as a child and the record was lost or misfiled.

Research into Nellie's subsequent whereabouts eventually found her in Gloucester, Massachusetts, married to a William Mitchell, with a son Linwood Arthur Mitchell, but no sign of Chester L. However, certain interesting coincidences led me to conjecture that Linwood might actually be Chester, informally adopted and renamed, with a delayed birth certificate naming William Mitchell as his father, and stating a birth date exactly two years (to the day!) after Chester's actual birth.

But, as I said in that post, "Of course, I can't prove (lacking DNA evidence) that any of this is more than just speculation."

What were the chances?

No, there had to be some other explanation. Probably the shared DNA amounts were misleading for some reason (some kind of double-cousin relationship? IBS?) and it really was one of the descendants of my half-aunt Hazel. For that matter, it was hardly out of the question that grandpa could have had additional off-spring that just never came to light before. So I never gave Uncle Chester any serious thought, and with no other apparent possibilities, I started researching Hazel's grandchildren to see if one of them had married into the surname of my new matches.

Two days later, I received an email from a young women who was doing some genealogical research for her grandmother and mother. A couple of months before, she had stumbled across this blog, with its two-year-old post idly speculating about the fate of one Chester L. Kirk. It made for eerie reading, she said, because her family lore held a rumor that her great-grandfather wasn't the biological son of his nominal father.

Her great-grandfather was named Linwood Arthur Mitchell.

Her grandmother – Linwood's daughter – and her mother had just received their DNA test matches.

To a half-first cousin, and a half-first cousin once removed, respectively.

To me.

What were the chances?