GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2005-06 > 1118935275


From: Ruy Cardoso <>
Subject: Re: [DNA] Overall Genetic make-up----comparing Y DNA/mtDNA tests with BioGeographical tests
Date: Thu, 16 Jun 2005 08:21:15 -0700 (PDT)
In-Reply-To: <200506160938.j5G9cag3019580@lists5.rootsweb.com>


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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