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Archiver > GENEALOGY-DNA > 2012-03 > 1332387612


From: (John Chandler)
Subject: Re: [DNA] Phasing 4th Cousins
Date: Wed, 21 Mar 2012 23:40:12 -0400
References: <4F6A49C2.5010505@yahoo.com> <REME20120321183300@alum.mit.edu><C77D5C96-82B9-4382-B733-ECDA769836DF@verizon.net><REME20120321215901@alum.mit.edu><6F17482E-20A6-461E-9B6D-B3E48E47A680@verizon.net>
In-Reply-To: <6F17482E-20A6-461E-9B6D-B3E48E47A680@verizon.net> (message fromJim Bartlett on Wed, 21 Mar 2012 22:22:54 -0400)


Jim wrote:
> Thanks - I'm thinking of a patchwork effort. In the end we have the
> whole quilt. And I think we would wind up with 2 quilts - one for
> maternal side and one for paternal side - and this would be true for
> each person in our ancestry.

In fact, our ancestors are bound up in pairs, and the quilts would be
produced together as one batch of 4x22=88 for each pair. Those
ancestors who had children by multiple spouses would entail larger
batches.

> If we limit this to large segments, known to be IBD (say over 10cM
> each), the paternal/maternal quilts would have a lot of small holes.

Consider: for even a pair of MRCA's just 6 generations back, the
chances of sharing a segment that large with another descendant are
something like 10%. It takes a lot of descendants to end up with
more "quilt" than "hole".

John Chandler

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