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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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