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Archiver > APG > 2009-04 > 1240416735


From: "robert mclaren" <>
Subject: Re: [APG] DNA information needed
Date: Wed, 22 Apr 2009 12:12:15 -0400


Judy,

The simple answer is that such a relationship cannot be proven through DNA
alone -- at least as the technology stands today. You don't say what type
of DNA testing was done (Y-DNA, mtDNA, or other), but this will not make a
difference to what I say.

The basic problem is that DNA testing will tell us that people are related
but not how. In some cases, the how can be determined through DNA, but
that is rare. For example, my male descendants will know that they descend
from me, not one of my brothers or and cousins. This is because I have two
mutations in my 67-marker Y-DNA test. However, to establish this required
me to test both of my brothers. They were identical (the most likely
outcome between brothers), but I had differences on two markers. So, I am
the one with the two mutations. (BTW, I also tested one of my grandsons
and we match 67/67.)

So, to be able to tell that Giles was the son of James, we will need a
number of Y-DNA tests and luck. The luck comes in if James had an
identifying mutation. Let's assume that he did. Then we would need to
compare a direct-line male descendant of Giles with a proven direct-line
male descendant of James. If they match, or come close to matching, they
are related. However, at this point we don't know how. So, now we need to
establish that James had brothers and and test a straight-line male
descendant of at least two of these brothers. Furthermore, since we are
looking at a number of generations, we will likely have to test more that
one straight-line descendant of each brother. This is to rule out
non-paternity events plus other intervening mutations. If James did have a
defining mutation, and if sufficient DNA testing was done, we could
establish that Giles was descended from James.

One last word. If you look at what has to be done, there is quite a lot of
genealogical investigations involved. So, I would hesitate to same that
Giles was proved to be a son of James by just DNA alone!

Please note that I am speaking about DNA testing as it applies to
genealogy. This is quite different from the CSI type of DNA testing which
is specifically designed to see if a DNA sample came from a specific
individual (which does require a DNA sample from the individual) or from
paternity or sibling testing which again requires the individuals in
question to test.

Yours aye,

Bob McLaren
Chairman, Genealogy Committee, Clan MacLaren Society of North America
Genealogist, Clan MacLaren Society (based in Scotland)
Administrator, Clan MacLaren Surname DNA Project (Worldwide) -- now at 389
Y-DNA members
Administrator, Lindo, da Silva, and Braham Surname DNA Projects (all
Worldwide)
Member, Association of Professional Genealogists


> [Original Message]
> From: <>
> To: <>
> Date: 4/22/2009 10:23:07 AM
> Subject: [APG] DNA information needed
>
>
> I need some help understanding DNA ancestry searches. Right now my head
> is spinning. I have had several clients who worked with DNA companies.
One
> client was traced back to a William Lee. However, William had a number of

> children and there was apparently no way of knowing which of them had
been my
> client's ancestor. I was hired to trace forward from William. Another
> client learned that she and another researcher had an ancestor in common,
but
> did not know who (accept for the surname). I understood those.
>
> But this client has posed a different problem. She contacted someone on
> one of the message boards who had claimed James and Mary were the
parents of
> Giles (bc 1822). The surnames of James and Giles is unimportant, but
> Mary's maiden name was Giles. And so, although this connection has been
> considered a strong possibility, no proof as been found. Both Mary and
James left
> wills and neither mentioned Giles. When my client contacted the woman
from
> the board asking what proof she had, the poster said the information
came
> from GeneBase BioNet.
>
> Can anyone explain how the relationship of Giles to both of these
supposed
> parents could be proven solely through DNA. Science was never one of my
> strong areas in school, so please answer as simply as possible..
>
> Judy Jacobson



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