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Archiver > GENEALOGY-DNA > 2004-01 > 1073073686


From: "Nancy Custer" <>
Subject: RE: [DNA] Question for you scientists!
Date: Fri, 2 Jan 2004 12:01:26 -0800
In-Reply-To: <3FF5C853.000001.01856@computer>


Debby,

In practice, the analysis of the X chromosome faces the same limitations as
the rest of the chromosomes. Unfortunately, it really isn't possible to
determine which of the X chromosomes comes from your mother and which from
your father. In addition, there is considerable cross-over between the two
X chromosomes during meosis so each X chromosome is a blend of many
ancestral X chromosomes from both the paternal and maternal lines. (I have
an animation of cross-over at
http://www.contexo.info/DNA_Basics/Meiosis.htm)

True, we can wring some small amount of information about our maternal lines
from mitochondrial DNA but for most genealogical purposes we are stuck with
the Y chromosome. It isn't chauvinistic, it's just what we've got.

Nancy

To answer a similar question posted earlier today, it is also not possible
to know which nucleotide in the pairs in the DNA Print test report you
received from your mother and which from your father.

> -----Original Message-----
> From: Debby Peare [mailto:]
> Sent: Friday, January 02, 2004 11:37 AM
> To:
> Subject: [DNA] Question for you scientists!
>
>
> I've been watching the discussion of
> the different tests and results of the
> DNA "Y" chromosone for awhile now.
> And, I think it's great! :-) But why aren't
> there any tests for the "X" chromosone?
>
> Males are "XY"...the "X" from Mom,
> the "Y" from Dad. And it's the "Y"
> that is tested.
> Well, females are "XX"...first "X"
> from Mom, second "X" from Dad.
> So, tell me, why can't that second X
> be tested as it has to be different from
> Mom's X, or you'd be a clone of Mom!!
> And, why aren't any tests being done with
> the first "X"....Mom's contribution?
> Seems to me that Mom has SOMETHING
> to do with the offspring's DNA ethnicity,
> and makeup, doesn't she?
> Looks like maybe we're being a wee bit
> chauvinistic in research here, aren't we?
>
> Warm regards from Maine,
> Debby Peare
>
>
>
> ==============================
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