Last week I linked to Genomes Unzipped participant Joe Pickrell ("Ancestry unzipped"), who was working through the ancestry calculations that made his genome appear to have been partially Ashkenazi Jewish in origin ("Am I partly Jewish?").
Now, Pickrell updates the story ("Am I partly Jewish? An unexpected turn of events"):
As I was mulling over these sorts of issues, I sent the link to my previous analysis to a family member. I didn’t really expect this person to find it that interesting, but hey, you never know. I then got a phone call. I’ll summarize a couple days worth of moderate confusion, second-hand reports of conversations with distant relatives, and family intrigue with this: as it turns out, one of my great-grandparents was indeed a Polish Ashkenazi Jew who immigrated to the United States around the turn of the century. I, obviously, was completely unaware of this.
Before coming to this deeper genealogical discovery, Pickrell summarizes some additional comparisons that made it difficult to explain the genetic results by errors in assumptions of the methods. This is the kind of outcome many people are hoping they will get from their genetic information -- a prompt for distant relatives to uncover family histories that, in many cases, they didn't know would be interesting. Or that in the past some wanted to forget.
Razib ponders the question "Do ancestors matter?" Obviously they matter deeply to some, to others not so much. Unexpected discoveries from genetic information are not new, they're at least as old as blood typing. There is already a large community of people who find meaning from genealogical research and comparisons with others -- research that ultimately can illuminate only a very small part of any individual's genealogical history. Genetics doesn't necessarily offer any more than this. Any one person's genes come from only a small fraction of her ancestors.
But the DNA may inform about a different part of one's genealogy than oral and written history. And it may give rise to a deeper idea of ancestry than cultural reckoning -- which in a mere fifty years can drive people to forget some of their ancestors and promote fictive ones.