There was an exception this week, which, once again, highlighted the random nature of autosomal dna inheritance.
But more importantly, they brought attention back to the Mary McEWAN that had been sitting in my database for many years potentially marked as being the daughter of James McEWAN and Mary McLAREN, and thus niece of my 3*great grandmother Margaret McEWAN.
This potential duplicate for Mary had married a William DUNCANSON and emigrated to Tasmania in 1855. Others have long ago connected the families up as one and the same, but her age didn't quite match, although census data did place her in the right places about the right times, among other candidates.
This time around I found her death entry, which squashed my qualms about her age, although no parents were indexed.
This, coupled with a dna match between a descendant of Mary's and myself, and to my third cousin once removed, both of us descendants of Margaret McEWAN, Mary's aunt, means that she has been connected up to the family and a heap of new McEWAN descendants formally welcomed to the database.
For those interested in further technical detail:
Autosomal dna (atDNA) is the part of our genetic heritage that we inherit randomly from all of our ancestors, as compared to the mitochondrial dna everyone inherits from their mothers but only daughters can pass on to their children, or to the Y-DNA that sons inherit from their fathers, passing that inheritance on to their sons in turn. Both of the latter are far more certain at surviving the transmission process from parent to child more or less intact, but the former is a bit of a lottery as to what survives from which ancestor.
We now have autosomal dna (Family Finder) results from four descendants of Archibald & Margaret (McEWAN) HENDERSON, and now one from a descendant of Margaret's brother James.
The only match that showed initially on Family Tree DNA, at the default settings, was between myself and my second cousin. Disappointingly no match shows up between myself and another descendant of our shared James and Amelia (MILLAR) HENDERSON, nor between any of us to the descendant of James' sister Margaret, although the latter was not entirely unexpected. This sort of test is really only expected to detect significant matches back to a shared 4-6 generations ago, so it's always a bonus to find a match further back.
Further exploration via GedMatch, where the parameters may be tweaked, revealed that there are several matches slightly below the matching threshold used by FamilyTree DNA between at least three of us after all. Mostly between the descendant of the two Margarets, one the daughter of Archibald and Margaret (McEWAN) HENDERSON and the other the daughter of James & Amelia (MILLAR) HENDERSON. Could be completely random coincidence (called Identical by State, rather than the Identical by Descent that we are after) of course, but I prefer not to think so.
We now have this growing scientific evidence that supports our paper trails, and provides a good solid base for future matches to pinpoint where they might be from.
But it would be even better to get representatives to join the fun and add to the evidence for the less defined paper trails, those for Margaret and James' siblings William, Archibald, and John, who either emigrated themselves, or many descendants did, to Australia, America, and Canada respectively.
I'm pinning my hopes on FamilyFinder evidence for William and John as both lines are rather short on direct male line HENDERSONs able to represent them. A Y-DNA representative may eventually be able to be found for Archibald's line, but a FamilyFinder match would also be very welcome!