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From:
Subject: Re: [DNA] Family Tree DNA
Date: Tue, 31 Oct 2000 16:19:29 -0800
References: <000b01c04300$cc898740$9375b4d0@tyler.net>


Hi Robert

Thanks for the questions on the Y chromosome side of genealogy and genetics.

> 1. How may generations can the test go back to, what I mean, say that
> my ggggg grand father had a brother. I met one of his brother's
> descendants, say in my generation. Would it be possible to determine
> that he and I had a common gggggg grand father, or just how far back
> could it be determined.

With Y Chromsome testing you can project back a few score of generations. In
our test we currently use 12 markers, so if you and the other person on the
GGGGG Grand Fathers side matched 12/12 we would know that you two shared a
common ancestor (99.9%) What we cannot tell is how far back in time the two
of you actually shared that common ancestor, however if you share a common
name the assumption must be made that the Most Recent Common Ancestor (MRCA)
would be from when your paper trail ended and the advent of the use of
surnames in the area where your family lived. A 12/12 match would rule out
two people choosing the name because it sounded good, etc. It would also
eliminate the possibility of un-announced adoption or false paternity.

> 2. Like wise, would it be possible to estimate how far back the
> connection might be.

Answered above...or at least I made the attempt :)


> 3. I assume that once I had a DNA test, from there on it could be used
> to compare any future tests from some one else.

Yes, in fact with our company we database your scores in our private,
off-line database and when someone comes into the database that matches your
alleles exactly, we will notify you that a genetic relative has shown
up...provided you and they have sign a Release Form giving us permission to
cross notify.


> 4. What effect would it have on the test where some one had married a
> blood cousin, in my family line it appears that, that happened often.
> Any where from a first cousin to a fifth or sixth cousin. So the blood
> might be a little mixed up if you know what I mean.

It would have an affect on the recombining portion of the chromosomes,
however not on the non-recombining mtDNA or Y chromosome.


Bennett Greenspan FTDNA Houston

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