French Canadian genomics and family histories are rich research territory

This fascinating Discover blog-post looks at recent research into the history and genomics of French Canadian families — who have a high propensity for Mendelian disorders, as well as relatively well-documented family histories — a combination that is proving to be a bonanza for researchers.

What has all this told us? From a medical genetic perspective it is implying that population structure matters when evaluating French Canadians, an Acadian is not interchangeable with a native of Montreal. In terms of ethnically clustered diseases of French Canadians, in the USA the Cajuns, it may not be that there are patterns across the whole ethnic group, but trends within subgroups characterized by long-term endogamy. I wonder if the same might be true of Ashkenazi. Is there is a difference between Galicians and Litvaks? Such regional differences among European Jews are new, but the French Canadians themselves are the result of the past three centuries. These results also seem to reinforce the Frenchness of the French Canadians. Years ago I skimmed a book on the cultural history of the people of Quebec, and the author went to great lengths to emphasize the amalgamative power of the French Catholic identity in Canada. Arguing that to some extent the roots of the community in the colonial era was something of an overblown myth. These results come close to rejecting that view. In particular the first paper, which shows the disproportionate impact that earlier settler waves have on the long term demographics of a population. A group which one could analyze in a similar vein would be the Boers, who are an amalgam of French Protestants, Dutch, and Germans, but seem to exhibit a dominance of the Dutch element culturally.

Finally, the French Canadians may give us a small window in the long term demographic patterns and genetic dynamics which might be operative on a nearby ethnic group: the Puritans of New England. Because of their fecundity it seems likely that tens of millions of Americans today descend from the 30,000 or so English settlers who arrived in New England in the two decades between 1620 and 1640. This is the subject of the Great Migration Project. With numbers in the few tens of thousands it seems unlikely that much of a thorough population bottleneck occurred with this group in a genetic sense in the aggregate. But the results from the French Canadians indicate that isolated groups can be subject to stochastic dynamics, and develop in their own peculiar directions.