|Some of my kits on GedMatch. Yes, there are a lot.|
People get excited when they see they match 5 (or 10 or 25) of my kits--but often they're kits from relatives on various branches of my family. So while these matches are related to me, they're not related to one another. Because endogamy means that Jews tend to get a LOT of matches, pretty much anyone with Jewish ancestry will match at least one (and probably multiple) of my kits. I get excited by those who share large segments or who match multiple cousins who themselves share common ancestors.
So while matching several of my kits generally isn't so exciting in terms of finding a relationship, Louis Kessler noted that individuals who match myself and Israel Pickholtz (who has even more of a DNA addiction than I) can use that fact to confirm Jewish ancestry. He introduces the Pickholtz-Diamond Index of DNA Ashkenazi Jewishness (PD Index) which gives a measure of how many Pickholtz & Diamond matches an individual has.
My internal geek has been ruminating over the various complexities of such an index (even if the name made me giggle when I saw it when I woke up this morning). If this really gets used, there are a few issues that would need to be addressed.
- One's PD Index can periodically change as either Israel or I test new relatives.
- Some of my relatives are not 100% Ashkenazic Jewish--so how would we know if the connection is via their Ashkenazic DNA or the DNA from another ancestral line? I know some of Israel's relatives also do not have 100% Jewish ancestry as well. (Also, I administer a kit for a friend who has no Jewish DNA whatsoever. So drawing conclusions of Jewish ancestry for matching her kit would be very incorrect.)
- Israel and I have ancestry solidly in Eastern Europe for at least the past few centuries. Is there a Sephardic genetic genealogist who has similarly tested many relatives? How about someone with strong German or French ancestry? We'd need to have a good representation of Jewish communities from around the world to make this truly useful to everyone.
Note: I'm on Twitter. Follow me (@larasgenealogy).