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Archiver > GENEALOGY-DNA > 2002-05 > 1022449823


From:
Subject: [DNA] Re: Huntley near-match
Date: Sun, 26 May 2002 17:50:23 EDT


In a message dated 05/25/02 11:04:56 AM Pacific Daylight Time,
writes:

> A gentleman has e-mailed me stating that his DNA matches mine except for a 1
> step mutation at 2 loci. His surname is different. Is he then a Huntley
> as I am or do we have a distant common ancestor?

If this is the only thing you know -- that you match at 10 out of 12 loci --
then you could apply the statistical calculation for the Most Recent Common
Ancestor ( http://www.members.aol.com/dnacousins/MRCA.exe ). The median
number of generations for two RANDOMLY selected people to reach their MRCA is
61.1 -- that is, 50% of cases would find their MRCA within 61.1 generations,
and 50% of cases would not. Surnames were probably not even in use that long
ago.

This large number is a little bit counter-intuitive, because when you look at
various surname projects, you can find numerous examples where two people
only match each other on 10 out of 12 markers, yet their known common
ancestor is only 10 or so generations back. The surname project covers lots
of transmission events from descendants in various lines, so some mutations
are to be expected. You can easily find two lines which have one mutation
compared to the common ancestor, but it's a different mutation, so those two
people differ from each other by two mutations.

I can't recall any cases where two people like you and your correspondent
have figured out their MRCA. But it never hurts to compare notes, and this
can inspire you to pursue your research for another generation or two.

Ann Turner
GENEALOGY-DNA List Administrator
http://lists.rootsweb.com/index/other/Miscellaneous/GENEALOGY-DNA.html
DNA preservation kits: http://www.dnafiler.com


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