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Archiver > GENEALOGY-DNA > 2002-09 > 1031080800


From: "John F. Chandler" <>
Subject: Re: [DNA] good article on Y chromo
Date: Tue, 3 Sep 2002 15:20 EDT
In-Reply-To: DNACousins@aol.com message <27.2cea933c.2aa4c6be@aol.com> of Mon, 2 Sep 2002 07:50:57 -0600


Ann wrote:
> Some have asked about how the terminology in this article (haplogroups)
> relates to results from genealogical testing (haplotypes). I've tried to
> explain this many times in many different ways, but I guess I'm not getting
> though, so maybe somebody else could take a stab at it.

I believe you really are getting through, but the constant growth of the
list is bringing a constantly fresh audience. There is just one thing
I'd like to add. Even though haplogroups are mostly of interest just
in population studies, there *IS* a reason why they keep coming up in
discussions here and why they can also be useful (in a broad way) to
genealogists:

WHEREAS there is a good correlation between the STR haplotypes measured
in genealogical DNA tests and the haplogroups used in population
studies, and
WHEREAS the modal haplotypes associated with the various haplogroups
are very different, one from another, and
WHEREAS two people whose haplotypes are anything like as different as
that are definitely NOT RELATED,
THEREFORE a person who can be reasonably assigned to one haplogroup
can quickly and easily be described as NOT RELATED to any member of
a different haplogroup.

(It's the "quick and easy" part that makes this useful.)

In other words, if your haplotype falls into one of the haplogroups
by a near-perfect match to the modal haplotype, you haven't learned
who your relatives ARE -- you have learned who they ARE NOT. This can
(and should) be some consolation to those who find that they have 11/12
or 12/12 matches with a host of different surnames. The key point often
is that they are very different from many individuals with the SAME
surname, who can therefore be ruled out as possible sharers of a common
ancestor.

John Chandler

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