Archiver > GENEALOGY-DNA > 2010-02 > 1266250263

From: Robert Stafford <>
Subject: Re: [DNA] TMRCA assessments
Date: Mon, 15 Feb 2010 10:11:03 -0600
References: <><AED0EBD31A11450093AC618E9997AD27@anatoldesktop>
In-Reply-To: <AED0EBD31A11450093AC618E9997AD27@anatoldesktop>

I have already answered the question, but will repeat what I wrote three
days ago:

In its genealogical usage, a parallel mutation is the same mutation observed
in two different lines in the same family. They are very significant in
genealogical testing, since people often assume that the two belong to the
same branch in the absence of a paper trail to their common ancestor or
might question their genealogy. However, testing other branches may resolve
the question in the former case and will usually do so in the latter.

It is also applied to ancient ancestry, especially to the the SNPs defining
haplogroups where it can be verified. It seems to be used for ancient STRs
in a theoretical sense.

The chance of an occurrence is purely mathematical and depends only on the
number of mutations and number of markers tested. Of course, the former
depends on the overall rate, the number of people tested and the
relationship structure.

The main relevance to the discussion is that someone apparently told David
that they were rare in a genealogical time span. This is a common
misconception among those who have not crunched the numbers and/or do not
have many test subjects per family.

Bob Stafford

On Sun, Feb 14, 2010 at 10:41 PM, Anatole Klyosov <>wrote:

> >From: Robert Stafford <>
> >I agree with you that back mutations are not worth discussing.
> >However, parallel mutations are much more common,
> >which can be shown by statistics. I would suggest that
> >you address them.
> Dear Robert,
> I have asked here already twice -- what is so important about "parallel
> mutations"? Why are they different from all other mutations, that so much
> attention is paid to them? If we take, say, L21 dataset of 509 of 67-marker
> haplotypes, that is 34,103 alleles, how many "parallel mutations" the tree
> has? However, the dataset is perfectly the "first-order", is nicely
> described, shows excellent fit between mutation-counting and base
> haplotypes-counting results.
> So what is a big deal about "parallel mutations"? What are those "parallel
> mutations" anyway? If they form branches - fine, so what?
> Thank you.
> Anatole Klyosov
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