Friday, August 28, 2009

Where You Come From

A series of reasonable probabilities chained together often creates an improbability of result. However much we were taught this in math class – that 90% times 90% times 90%… very rapidly becomes a less than 50-50 chance – we resist the concept. We like to apply it to history, social policy, and why our relatives act the way they do. Just about everything. If Churchill hadn't mentioned that day...

This becomes a touch humorous when discussing genealogy. The general rule is that 5-10% of births every generation are “non-paternity events.” That is, the father of record is not the actual father. If you trace your line back and keep track of how many males you had to trace through to get to a particular person, after about 6 guys you are talking about folks who have a less than 50% chance of being a blood ancestor. 12 guys, 20%.

The worse news in this is that the surname line, which is by definition father to son and the one which folks are most interested in, is thus the most fragile genealogically. We are fond of saying things like “Well, we Wallaces came from Ayrshire in Scotland, mostly, so…” Yeah. Ancestors last in Scotland in the 17th C, via Ulster in the 18thC? Sorry Douglas, you might not be a Wallace. You might still be a Scot, of course, as they were the bulk of who would have been around for those non-paternity events.

The mother to daughter line, hardest to trace, is of course more reliable because even when the occasional mother or sister gets “credited” with a birth, it goes back into that line in a generation anyway. True, there are always unrecorded events of early widowhood and remarriage that obscure the biological line, but it’s still way better than the male percentage. You get some extra advantage if you are tracing back through heavily Puritan lines, or Cohen lines in Jewish heritage, because there’s evidence that they were down even below that 5% line. Everyone else, plan on 10%.

I’m sorry to insult your ancestors like this and knock the stuffing out of your DAR line, but that’s just the statistical reality.

As DNA evidence improves, we begin to be able to track a little better. In every surname line there seems to be numerically dominant genetic group which would have the strongest, though not indisputable claim to be the father-to-son surname line. There are usually a few other large lines, suggesting that those nonpaternity events occurred in the comfortably distant past, so you can at least claim your family has been Harrisons for several centuries (though not the Original Harrison).

We got lucky in our surname evidence. A picture of my great-grandfather Charlie Wyman in Nova Scotia looks enough like me, and even more like my brother, that we can safely start counting our six males back from there. And a good thing for future generations, actually. Though anyone who spent 10 minutes with my Dad and any of his sons would be overwhelmed by the resemblance of gesture and personality (even though two of us did not grow up under him), looking at a photograph wouldn’t give you much indication we were related. None of us looked like his father either, until the last year or so, when I started seeing him in the mirror. (You guys are next). But tentative conclusions I had reached about my general ancestry I am rethinking. My confidence in having a fair number of East Anglian forebears has waned recently. I doubt that many of you will be interested in the specifics of that reasoning unless one of the surnames jumps out at you as one in your own family tree; the reasoning itself and the collateral information may be of some interest. I’ll likely write that up over the weekend.


Donna B. said...

We sent a DNA sample from my father and it matches neither of the two "known" lines with his surname.

We're pretty sure there's a non-paternity event there. What was amazing was getting the surname that his DNA did fit in with. Not that there's much we see that we can do with that information.

You've just reminded me that I still have one document to submit to finish my DAR application. It's on my mother's side and I had a great head start there because my mom's sister started gathering family information in 1918.

karrde said...

I have an uncle who has traced the "official" genealogy for every member of the extended family, as far as he can.

Every once in awhile, at a family gathering, he will comment that so-and-so's fifth cousin's parents were found buried in some cemetary, and the archived obituary in the newspaper told him interesting things about the family tree.

To my knowledge, he doesn't know (or care) about the paternity issue you mention.

It's still interesting, though. We have the family tree in North America all the way back to a man who stepped off a ship in Boston Harbor in the 1650's.

But we have no records from London, which was his port of departure from the old world.

Assistant Village Idiot said...

karrde - if it was Boston, it was probably a touch earlier. The migration before Cromwell was Puritans going to NE. After Cromwell, it was royalists going to VA.

Not a lock, of course, as people did continue to come to NE throughout the 17th C. But the bulk came within a few years plus or minus from 1635.

karrde said...

I probably misremembered the decade in question...

Donna B. said...

There may well be a non-paternity event between me and my DAR ancestor too, but in a way it doesn't matter.

What I plan to do (and I should get hopping on it!) is write a personal history for my grandchildren so they have an idea of how their ancestors lived.

I want to make history a little more interesting for them, if possible.

The other grandparents of my only (so far..) grandchild have an immensely interesting history and I'm trying to convince them to do something similar.

When my other daughter has children, it will quite easy to do this as we've already found she and her husband have a common ancestor. Barring non-paternal events, that is.

Gringo said...

My confidence in having a fair number of East Anglian forebears has waned recently.

My understanding is that the bulk of the Puritan migration to NE was from East Anglia. My NE hometown has its twin in East Anglia. So if you have some old NE background, East Anglia is a fair assumption. We are awaiting your reasoning.

Much of my ancestry has the ornery gene: Scots-Irish and religious dissidents- Quaker, not Puritan in my case.

My sister-in-law has done a lot of genealogical research, and what has impressed her has been the number of double cousins, or of marrying the sibling of your deceased spouse. In such circumstances, a "false flag" father- the one on the marriage certificate- may have been already related to the actual father, thus not resulting in a big change in the DNA.