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Archiver > GENEALOGY-DNA > 2007-02 > 1171547598


From: Vincent Vizachero <>
Subject: Re: [DNA] How do you do an estimated Common ancestor
Date: Thu, 15 Feb 2007 07:53:18 -0600
References: <c1e.100543a9.3305453f@aol.com><7.0.1.0.0.20070214224123.0c934868@wells.org>
In-Reply-To: <7.0.1.0.0.20070214224123.0c934868@wells.org>


On Feb 15, 2007, at 12:58 AM, OrinWells wrote:

> You are also correct that I do make an intuitive assessment of a
> likely connection based on number of mutations. I have pretty much
> come to the conclusion that even at 43 markers more than three
> differences is probably enough to exclude the two from being closely
> enough related that we are ever going to find the confirming
> documentation.

Given that you yourself held out an example of two brothers having
an GD of 3, I have to say that it seems odd that you would adopt
such a crude rule of thumb.

Two people who are very closely related can have a genetic distance
much greater than three. TMRCA calculators incorporate the
probability of such an event while simplistic rules of thumb cannot.
That is their value.

Vince

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