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Archiver > GENEALOGY-DNA > 2005-06 > 1118960416


From: "louis" <>
Subject: RE: [DNA] Overall Genetic make-up----comparing Y DNA/mtDNA tests with BioGeographical tests
Date: Thu, 16 Jun 2005 15:20:16 -0700
In-Reply-To: <20050616152115.78185.qmail@web60916.mail.yahoo.com>


Hi Ruy and List,

Thanks for your response. Your points really helped me realize that I need
to re-explain my questions.

I think the best way for me to explain this is by using a hypothetical
example: Let's say I have my 16 g-g grandparents DNA fingerprints, and I
find out that they are as follows:

1) Loccisano--G2 (Persian origin)
2) Papallo--R1a (Slavic origin)
3) grandfatherX---K2 (Arabic origin)
4) grandfatherP---O2 (Chinese origin)
Assume the rest of my 8 great-grandfathers are all G2 (Persian origin)
Assume all 8 of my great-grandmothers are mtDNA Haplogroup H1a (Spanish
origin)

Then, it follows that I know all 16 of my g-g grandparents origins, but even
though this makes up 100% of my genetic make-up, I still don’t know as much
about my ancestors as if I knew ALL 32 great-great-great grandparents
YDNA/mtDNA. Having 32 g-g-g grandparents DNA fingerprints, is much more in
depth than having only 16 g-g grandparents DNA fingerprints. It doubles
thee amount of ancestors we know about! Therefore, some of these new
ancestors going one generation back in time could be, lets say, sub-Saharan
African origin and that would alter the ethnic % of my genetic make-up.

So I guess, I want to know how many generations back would you need to go to
get a very high resolution of your ethnic origins?

Does this make sense? I guess having all 16 gg grandparents makes up 100%
of your genetic make-up, as does having all 32 ggg grandparents, but all 32
ggg grandparents has much more "resolution" and shows your ethnic backround
in much more depth.

Thanks!
Louis Loccisano



-----Original Message-----
From: Ruy Cardoso [mailto:]
Sent: Thursday, June 16, 2005 8:21 AM
To:
Cc:
Subject: Re: [DNA] Overall Genetic make-up----comparing Y DNA/mtDNA tests
with BioGeographical tests

Hi, Louis.

> From: "louis" <>
>
> QUESTIONS:
>
> 1) What % of my genetic make-up do these 16
> great-great grandparents lines represent?

I may not entirely understand the question because the
possible answers seem too obvious. If you mean what
percentage of all your DNA comes from these 16
collectively, then the answer is "all of it". If
you're asking how much each contributed, then the
answer is "about 1/16th, on average", but each
individual would have contributed a little bit more or
less than 1/16th. (Go back further in time and that
"a little bit more or less" will eventually become "a
large bit more or less"; eventually you'll get to a
point where a given ancestor may have contributed
nothing.) If you're asking how much of your Y-DNA or
your mt-DNA comes from these 16, then the answer is
essentially "all of your Y-DNA came from the male-line
ancestor and all of the mtDNA came from the
female-line ancestor".

Perhaps you're asking what fraction of all your DNA is
made up of Y-DNA or mtDNA?

> I have a feeling some people will say that comparing
> YDNA/mtDNA with autosomal DNA is like comparing
> apples and oranges. But I don’t agree with
> that logic.

It's not really a matter of logic; the different types
of DNA get to you by different paths. That's not to
say that there aren't relationships between them, but
see my next comment.

> In the future, I believe, we should be able to
> correlate the two if enough grandparents Y/mtDNA
> fingerprints are tested.

As a theoretical idea, this might be possible. But
the practical problem is that there are so many
possible combinations of autosomal DNA that the number
of markers examined would really have to be
outlandishly high to get results anywhere near
reliable.

Am I misunderstanding what you asked?

Ruy Cardoso

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