Ashkenazi DNA percentage question #dna


Herbert Lazerow
 

I have 1 known Ashkenazi great grandparent of 8. One eight is 12.5%.
According to 23andMe, FTDNA, AncestryDNA and MyHeritage DNA
my DNA is about 20% Ashkenazi. All agree on this. This is 1.6 times
more Ashkenazi DNA than I can account for genealogically. Is it more
likely that I have an undiscovered ancestor with Ashkenazi DNA, who
perhaps assimilated, or that I simply inherited more than half of my
grandparent's Ashkenazi DNA?
It is more likely that you inherited more than your proportionate
share of your ggp's dna.
We each receive half our dna >from each parent, but it is a random
half. Assume that your ggp had only 8 genes, A-H. Assume further
that your gp inherited 4 of them, genes A-D, 50%. Your parent would
have inherited 4 genes >from your gp. They might have been A-D, in
which case your parent would have 50% Ashkenazi genes. If your parent
inherited genes E-H, he would have no Ashkenazi genes. Either result
is possible, though neither is the most statistically likely. It is
more likely that your parent inherited 3, 2, or 1 Ashkenazi genes.
The same calculus applies to your inheritance >from your parent, which
is why it appears that you have more Ashkenazi dna than you "should"
have.
Bert
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Herbert Lazerow
San Diego CA 92110 U.S.A.

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