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Archiver > GENEALOGY-DNA > 2007-05 > 1178011436


From: John Cartmell <>
Subject: Re: [DNA] Double or single cousin?
Date: Tue, 01 May 2007 10:23:56 +0100
References: <c3c.12bb6671.33681c7e@aol.com>
In-Reply-To: <c3c.12bb6671.33681c7e@aol.com>


On 01 May, <> wrote:
> In calculating simple relationships, you need
> to multiply by 1/2 for every generation or first
> degree relative in your pedigree
> Example:
> 1/2 genes in common with a parent
> 1/2 X 1/2 genes in common with the sibling of a parent
> 1/2 X 1/2 X 1/2 to get to that sibling's child;
> that equals 1/8 genes in common with your 1st cousin.
> If you have double first cousins, you then need to add
> the probabilities 1/8 + 1/8 = 1/4, assuming no
> identical twins.

But beyond parents the calculations are based on probabilities and the reality
is both fuzzier and not calculated like that. As first approximations it will
do.

--
John 006 8822 or 0161 969 9820
Qercus magazineFAX +44 (0)8700-519-527www.finnybank.com
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