GENEALOGY-DNA-L Archives

From:
Subject: Re: [DNA] Is 23/25 markers a match?
Date: Fri, 3 Oct 2003 11:32:00 EDT

In a message dated 09/30/03 12:47:02 PM Pacific Daylight Time,
writes:

> I have recently been tested for a 25 marker Y DNA test and have a 2 step
> difference in DYS 385B and a 1 step difference at DYS 449 with some others in
> my group. My group administrator says a close relationship with those others
> is not likely even though these markers have been determined to be fast moving
> according to FTDNA. Do you agree or disagree with my administrators
> statement?.......John

Interpreting these statistics depends on your "prior knowledge." If the only
thing you know is that you have 2-3 mutations (depending on whether you count
DYS385b as 1 or 2) compared to another person, only a small percentage of
people would find their common ancestor in a genealogical time frame. There is a
graph at FTDNA with figures for the 1 one-step and 1 two-step combination.

http://nitro.biosci.arizona.edu/ftdna/23-1-1.html

It is based on the "average" mutation rate, so having mutations on the "fast"
markers would shift the curve to the left somewhat.

However, if you study various surname websites, it's not hard to find two
specific individuals, who have good paper trails to a common ancestor and yet
differ from EACH OTHER by two or even three mutations. However, there is usually
a "bridge" haplotype -- someone who splits the difference between them. For
example, the Mumma web site has established the ancestral haplotype, and some
branches have their own mutations. M21 and M36 differ from each other at two
spots, but differ from the ancestral haplotype at only one spot.

http://www.mumma.org/DNA.htm

If your "prior knowledge" (your paper trail) pointed to having a common
ancestor with the other Paces in the study, all is not lost. You could search for
descendants of other branching points, preferably finding your most distant
cousin, and see if his results split the difference.

Ann Turner - GENEALOGY-DNA List Administrator
Search or Browse the archives, Subscribe or Unsubscribe at
>http://lists.rootsweb.com/index/other/Miscellaneous/GENEALOGY-DNA.html
DNA preservation kits: http://www.dnafiler.com

This thread:

• Re: [DNA] Is 23/25 markers a match? by

  • Re: [DNA] Is 23/25 markers a match? by