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Archiver > GENEALOGY-DNA > 2006-02 > 1139656709


From: Robert Stafford <>
Subject: Re: [DNA] Earliest common ancestors for 37/37 and 43/43 matches
Date: Sat, 11 Feb 2006 03:18:29 -0800 (PST)
In-Reply-To: <7.0.1.0.0.20060210195842.10117e00@wells.org>


Parallel mutations are not unlikely. With 11 mutations from on 40 markers, the odds are about 50/50 that there are one or more parallel mutations. It is similar to the birthday paradox:

http://en.wikipedia.org/wiki/Birthday_paradox

To calculate the probability of one or more parallel mutations, use 2 times the number of markers (+ or - states after a mutation) instead of 365 and let n = number of mutations in the formulas.

We have two parallel mutations, in which the paper trails are supported by other branch tags on slower markers. One, on DYS439, is internal to a family for whom we know the MRCA. The other, on DYS459, is from a related family whose progenitor was a 42/43 match with him, the mismatch being the branch tag. We also have two likely ones on unconnected branches for which we haven't determined the haplotypes of the progenitors. We have a total of 26 participants in this group that seems to be closely related.

The families lived very far apart when the events could have occurred and were not very close cousins, so it is unlikley their paths ever crossed. Thus, a false paternity seems very unlikely.

Having encountered parallel mutations on markers that are not particularly fast, I wouldn't conclude that common mutations are branch tags without some paper trail to support it. This is especially true for very fast markers as they more likely to be involved.

Bob Stafford

OrinWells <> wrote:
It I would have to guess that the odds against such a parallel mutation down two separate branches even in the same family has to be somewhat near
infinite.


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