Riverman
07-09-2020, 01:06 PM
I asked the question in another thread, but got no answer and found nothing conclusive about it:
Looking at what companies like 23andme or Myheritage assign, most people with 4 Ashkenazi grandparents score especially on 23andme something like 99 % AJ. How far back would a recent admixture be recognised by the algorithm? If someone had 3 non-AJ ancestors in the 18th century, would that stick out? They wouldn't have been part of the bottle neck and being recent admixture instead, but still back far enough for being rather widespread and integreated in the local AJ gene pool. Yet they wouldn't be "common Ashkenazi", but restricted to only some locality and families. Where would those with experience for samples from different AJ groups draw the line between what's being commonly subsumed under AJ and what sticks out as newer admixture? Does it depend on the samples a calculator uses only? Like if the recent admixture being part of the reference, it wouldn't be recognised as "new admixture" in one case, while if the reference lacks it, it would? That way by having very large AJ samples, any newer admixture even from the 19th century might disappear?
There surely was admixture from the 16th to 19th century, as small or big as it might have been and the later it happened, the less widespread and generally Ashkenazi it can be.
Looking at what companies like 23andme or Myheritage assign, most people with 4 Ashkenazi grandparents score especially on 23andme something like 99 % AJ. How far back would a recent admixture be recognised by the algorithm? If someone had 3 non-AJ ancestors in the 18th century, would that stick out? They wouldn't have been part of the bottle neck and being recent admixture instead, but still back far enough for being rather widespread and integreated in the local AJ gene pool. Yet they wouldn't be "common Ashkenazi", but restricted to only some locality and families. Where would those with experience for samples from different AJ groups draw the line between what's being commonly subsumed under AJ and what sticks out as newer admixture? Does it depend on the samples a calculator uses only? Like if the recent admixture being part of the reference, it wouldn't be recognised as "new admixture" in one case, while if the reference lacks it, it would? That way by having very large AJ samples, any newer admixture even from the 19th century might disappear?
There surely was admixture from the 16th to 19th century, as small or big as it might have been and the later it happened, the less widespread and generally Ashkenazi it can be.