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Y Chromosome Genetics
Name: Stephen
Status: Other
Grade: Other
Location: N/A
Country: United States
Date: July 2005
Question:
Hello,
I am a male. My question is this: although I obviously have the same
Y-chromosome as my paternal grandfather's father, this would not mean that
I share a closer genetic relationship with him, as compared to the
relationship which exists between me and, let's say, my maternal
grandmother's father, would it? Because, as I understand it, the
Y-chromosome is just a "marker" (so to speak), and thus I should have
1/8th of each of these men's DNA, and might, in fact, have more nuclear
DNA from the maternal great-grandfather, although, I suspect, extremely
complex tests would be required to determine this, due to mutation,
re-combination, and so forth.
Replies:
It depends on the origin of your X-chromosome. It could have come from
either your maternal grandmother or your maternal grandfather. If it came
from your maternal grandfather, you would more resemble him. If it came from
your maternal grandmother, you would more resemble your paternal grandfather
because you received your Y chromosome from him which does in fact carry a
few genes besides the SRY region (sex-determining region Y).
Ron Baker, Ph.D.
You are correct. You are a genetic mix of all of your ancestors-with a few
exceptions! Remember that you receive 23 chromosomes from mom and 23 from
dad. So for the most part, you ARE a mix. But as a male, you inherit your Y
only from your dad, which is 1/23 of the chromosomes. And your dad inherited
HIS Y only from your paternal grandad, and so on. Some very interesting
studies have been done recently using certain markers on the Y to track
human migration. If this interests you, read the book "Adam's Curse" by
Bryan Sykes. A related phenomenon concerns your mitochondrial chromsome,
which is only inherited from your mother. It has nothing to do with
determining your sex, so all children of one mother inherit copies of her
mitochondrial DNA, but none from their father. The work on human migration
was originally done on mtDNA, but we now know we didn't have the whole
story. It seems that male migration patterns and female patterns are very
different as you might expect. Men do seem to wander, and females seem to
stay put.
vanhoeck
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