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From:
Subject: Re: [DNA] Filtering of Cousinships in 23andMe's Relative Finder
Date: Sun, 11 Oct 2009 17:41:35 EDT


But a females two Xs come from one of two sources, as I understand the
process. One comes from a recombination of her paternal grandfather's and one
from a recombination of her grandmother's. Her female offspring's X is one
or the other. The process of deactivation of one is random. If two sisters
tested with say FTDNA and 23andme which, I'd guess, from the use of saliva
and cheek scrapings, come from different types of cells. Two sisters, it
seems, would have a 50/50 chance of matching their X depending on the cell
type sequenced. If FTDNA and 23andme extract DNA from the same type of cell
then they can't detect the diference. But other cells might. On the other
hand the formation of the embryonic cells which lead to eventual production of
ova may only involve one of the two Xs exclusively. I haven't found an
answer.

Tom Butler



In a message dated 10/11/2009 3:54:52 P.M. Eastern Daylight Time,
writes:

I have little knowledge of terminology of the actual processes, males get
a set of the X-chromosome segments from his mothers two X and passes it
over to his daughter, thats is the basics I need to know from a ancestry
analysis perspective.

Anders



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