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From: <>
Subject: RE: [DNA] 35/37 Marker YDNA Advice Requested
Date: Mon, 20 Feb 2006 05:47:20 -0500


Nancy,

Thank you for your reply. Your web site and explanation of
molecular genealogy and mutations are concise and clear. This
is the first explanation that I, as a non-expert, can understand.

We have been gathering data on three families (E, C & D) for
the past 4 years and now have over 2000 family members. In
the Spring, we hope to give this info to the PA and OH
genealogy societies and to other relevant forums.

In our family (Sheehan, Shehan, Shahen) the dilemma is the
connection to "A", who fought in the Revolutionary War and is
recognized as a DAR patriot, ancestor of "E". The family lore
for "C" also claims to be a descendant of "A". This would only
be possible if "A" had two spouses and families, the first in
Pennsylvania when he was young (about 21) with a son, John,
who is the ancestor of "E"; and the second with a different
spouse in Ohio when he was older (about 45) with a son (also
named John) who is the ancestor of "C". Would we be correct
in saying that the DNA results (35/37) do not invalidate this
conclusion, which statistically could occur in about .14679
cases--not the most common scenario but solidly possible? Or
how would you phrase this?

I really appreciate your taking time to respond to my naive
questions.

Patricia

---- Original message ----
>Date: Mon, 20 Feb 2006 00:10:44 -0800
>From: "Nancy Custer" <>
>Subject: RE: [DNA] 35/37 Marker YDNA Advice Requested
>To:
>
>Patricia,
>
>It looks like this went unanswered unless someone replied off
list.
>
>Mutations are random and they have to happen somewhere. I
(as have a lot of
>other people) have made an attempt to explain the biology of
mutations at
>http://www.contexo.info/DNA_Basics/molecular_genealogy.ht
m A 35/37 marker
>match (yes that means two mutations) over that distance is
certainly
>acceptable--especially since it is supported by a common
surname and
>traditional genealogy.
>
>Using Ann Turner's mutation calculator
>(http://members.aol.com/dnafiler/MutationCalculator.exe)
with a mutation
>rate of .002, you will find that two mutations between people
separated from
>a common ancestor by five and six generations respectively
can be expected
>in about .14679 cases--not the most common scenario but
solidly possible. I
>have very few exact 37/37 marker matches in my project of
50+ Dorseys. They
>are not all from the same line but some are well known to
each other as
>cousins.
>
>CDYa is a marker chosen by Family Tree DNA because its
relative volatility
>makes it potentially useful in identifying branching points of
closely
>related lines. Just think, if there were no mutations, we
wouldn't really
>learn much from DNA testing. There is a mutation at YCAIIb
between my
>husband and our son.
>
>Nancy
>
>-----Original Message-----
>From:
[mailto:]
>Sent: Sunday, February 19, 2006 3:41 AM
>To:
>Subject: [DNA] 35/37 Marker YDNA Advice Requested
>
>I would like the opinions of people who have experience in
>analyzing DNA as it is applied to genealogy. I know that the
>expertise from this group is far above my level. However, our
>family genealogy is stymied, and we would greatly appreciate
>advice and comments.
>
>We have a 35/37 marker test result for which we need
>some clarification as to the possibilities of relationship within 6
>generations of the Most Recent Common Ancestor (same
>surname).
>
>Paper genealogy shows that "A" and "B" were brothers in the
>mid 1700's.
>
>There is an exact match of 37/37 markers for same surname
>"C", a five generation descendent (177 years) of "A", and
same
>susrname "D", a five generation descendent (169 years)
of "B"
>
>But, my question is about "E". Paper genealogy indicates
>that "E" is a 6 generation descendant (189 years) of "A".
>However, "E" only matches "C" and "D" 35/37: with marker
447
>one point different and marker CDYa one point different.
Could
>this be due to mutation? Do mismatches for either of these
two
>markers have a special significance (slow or fast changing,
>etc.)?
>
>What are the chances that "E" is related to "C" and "D" and
>that "A" is the MRCA of "E" as indicated by the paper
>genealogy?
>
>Thanking you for your advice,
>Patricia
>
>
>==============================
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>
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>
>==============================
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