The Art of Finding Ancestors
I’ve recently tested at AncestryDNA which is a DNA service of Ancestry.com the famous genealogy research company with 2 million subscribers. I’ll get into the nuts and bolts of DNA testing at Ancestry soon but for tonight I want to talk about my French Canadian ancestry and how difficult it is for an adoptee to figure out their French Canadian heritage.
It is difficult for adoptees to identify their ancestry no matter what their heritage. They have to find several, three to six, DNA cousins who have good trees and whose ancestry overlaps. The first thing you hope for is to find where your DNA matches share an ancestral couple. Once you find that couple common to two cousins you then can normally look back and forward from that couple and try to find other cousins that connect into the descendants of this pair (or their ancestors as a second choice). It’s better if you can find a cousin that matches up with a descendant because that gets you a little closer to your parents. Let me put a warning though, just because two people are related to you and share a common ancestor is no guarantee that they are related to you in the same way. But in general, this is a good starting point. On the other hand, if you’re trying to break through a brick wall, the same methodology works but you’re looking for folks that match further back.
Sometimes, it’s only one person shared between your matches as some ancestors have more than one spouse. If one of you descends from one spouse and the other person This actually causes a diminished estimate of the closeness of a cousin because you are inheriting the shared DNA from only one person instead of the normal two. If this happens, you may be more closely related than you thought but only if the multi-spouse event is right at the most recent common ancestor between you and your matches.
Confounding French Canadians
So how does being French Canadian add complexity to the already difficult task? Remember when I said that there is no guarantee that you’re related through the common ancestral pair of two cousins? Well, that’s increasingly true among French Canadians because there were very few original founders of Quebec, Newfoundland, Arcadia and to a lesser extent, Ontario. By the time you trace back the ancestry of any two random Québécois descendants to the early 1600′s there is guaranteed to be a common ancestor because in 1663 there were only 3,000 Europeans in all of New France. Note, that’s not 3,000 unique families just 3,000 people. Soon after that there was an influx of soldiers and 700 fils du roi, single women shipped to New France by the king of France so that the men had European women to marry. The total number of Immigrants from France hit about 10 thousand by 1680 when the crown halted immigration. These 10,000 French were spread from Louisiana, up through Missouri, Michigan, especially Detroit and it’s Upper Peninsula, and of course New England, Quebec, Acadia, Nova Scotia and New Brunswick. Despite the efforts of the British who deported seven thousand Acadians many of whom escaped to Louisiana, the French populations continued to increase with families frequently having 15 or more children. The French population tripled between 1717 and 1755, and has since ballooned to 6.3 million French-speaking people in French Canada today plus all those who immigrated to New England, Michigan and Louisiana and their descendants.
This kind of exponential population growth from a few individuals is a bottle neck in the parlance of population genetics. This intermarrying creates amazingly complex family trees with enough interweaving of familial lines that they look like a six-year old’s first macrame project. They also blur the lines between IBS only and IBD segments — because while those segments are technically traceable in a genealogical sense, they are so shuffled through the population that it’s impossible to be certain what path the segment came through to the current population. Let the confounding begin!
One of the problems with this kind of decendancy is that sometimes the segments gang together to create either an increased number of segments or much larger segments than would be realistically expected at that cousinhood if they overlap. The former is a big problem for relationship predictions at any of the big three, 23andMe, FTDNA or AncestryDNA but is the biggest problem for FTDNA who count these tiny segments but don’t phase the chromosomes [ie separate mom's chromosomes from dad's.] The latter problem exists only at FTDNA and 23andME because AncestryDNA phases the chromosomes they don’t get ‘fooled’ by overlapping segments.
In any case, it’s impossible to know when these segments have come from one ancestor or another more distant ancestor. Some folks are trying to track segments but when you have an inbred population that’s not really possible. It’s true that segments travel vertically in trackable ways, but they don’t often travel horizontally, ie through siblings, in a reliable, trackable way. And when cousins are kissin’ cousins… it’s like playing “find the pea” and you’re the shill!.
What to Do?
Clearly, tree matches that are further back in time along a French Canadian line are suspect but where do you draw the line? I’ve chosen to draw the line at 1675 because a few years later the population was at ten thousand which seems a reasonable level and this was a generation after the last major influx of women, soldiers and other French colonists. As a side note, French Canadian generations are both shorter and less precise because those women were popping out babies every 2 years often starting from a very young age. In other populations the generational time is closer to 30 years but with the early French Canadians I usually think of a generation as 25 years. I don’t ignore matches that are further back thank 1675, of course, but I weight them as far less important and require many more relatives to match at that level for the ancestral pair to be meaningful.
Please read on here [Unraveling French Canadian Ancestry] to see how I’ve applied these principles in trying to trace one line of my genealogy. This article also gives further tips on how to handle interwoven relatives.
Sources: History of New France