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Archiver > GENEALOGY-DNA > 2010-09 > 1284242240


From: Gregory Magoon <>
Subject: Re: [DNA] Experimenting with Family Finder Chromosome Browser
Date: Sat, 11 Sep 2010 17:57:20 -0400
References: <8CD1FFBC72736E3-1680-C8C3@Webmail-m109.sysops.aol.com>
In-Reply-To: <8CD1FFBC72736E3-1680-C8C3@Webmail-m109.sysops.aol.com>


Kathy, I think I am beginning to understand your argument better. If
I'm understanding you correctly, you are considering the possibility
for a pair of individuals to match on what appears to be a single
segment through multiple unrelated ancestors (and the two pieces may
be on separate homologous chromosomes). Ignoring false positives,
etc., it would seem to me to be somewhat unlikely for a pair of
individuals to share in this manner, as it requires both individuals
inherit the common DNA from two lines (not just one) in the same
chromosome region. And for a three-way match to occur with everything
working out as you describe seems quite unlikely to me, but I will
agree that it is possible.

As for the puzzle, if I correctly understand the problem you are
posing, this can be done with as few as 3 SNPs
1: GT, GT, TT
2: GT, TT, GT
3: TT, GT, GT
4: GT, GG, GT
5: GG, GT, GT
6: GT, GT, GG

Greg

>
> The real winner is the person who can come up with an example of a
> string of no more than lets say, 9 base pairs all showing the above
> matching and mismatching  of potential cousins. Just pretend that the
> sequences go on for 20 cM. You will also have show how to phase strings
> A, B, C and any others you may find.
>
> Cousin 1 must not match 6,
> Cousin 2 must not match 4,
> Cousin 3 must not match 5,

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