GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2003-01 > 1041907745


From: OrinWells <>
Subject: Re: [DNA] Y test - random samples
Date: Mon, 06 Jan 2003 18:49:05 -0800
In-Reply-To: <20030104.215646.-1706033.0.petticrewga@juno.com>


At 09:56 PM 1/4/2003 -0700, George A. Petticrew wrote:


>On Sat, 4 Jan 2003 22:30:10 EST writes:
> > The subjects are two brothers who matched 12/12. Their first cousin
> > matched
> > 9/12. We believe we know the generation where the "event" occured,
> > but I
> > keep wondering if I should take a closer look.
>
>How is this possible? From the probability numbers I have read in this
>list for 12/12 matches, I would think the odds against a 9/12 in TWO
>generations must be astronomical!!! Can some of you pros comment?

Keep in perspective that Suzanne was asking about a suspected "non-paternal
event" here. Not that they have a first cousin who didn't match. She
expected it. And it would appear she has this. 9/12 is a pretty clear
indication for first cousins that one of them is not sharing a common
grandfather with the other.

But, as I have noted previously, we have a case where brothers differ by 3
markers, although not in the common 12. This was apparently caused by some
outside influence for which we have no explanation. So it is very possible
for two closely related individuals to differ by several markers. This is
where the regular genealogical documentation can trump the DNA. The odds
of a non-paternal event leading to only 3 differences must be equally
astronomical.

To be certain, the 25 or 26 marker test is likely to show still more
differences in Suzanne's case.



Orin R. Wells
Wells Family Research Association
P. O. Box 5427
Kent, Washington 98064-5427
<>
http://www.rootsweb.com/~wellsfam/wfrahome.html
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