Unique gene

[t-star]

Just some crazy ideas I'm having that someone with a good understanding of genetics might help me with.

 

Would it be possible for a unique gene or gene combination to be passed down from ancestor to ancestor without anyone else having that gene, but that gene always being passed on? Maybe if all the ancestors only had a single child? So you'd be able to trace that gene back through the generations to an original and nobody else would have that gene/gene combination except one male/female ancestor, say great grandfather > grandfather > grandfather > son.

[steevey]

Just some crazy ideas I'm having that someone with a good understanding of genetics might help me with.

 

Would it be possible for a unique gene or gene combination to be passed down from ancestor to ancestor without anyone else having that gene, but that gene always being passed on? Maybe if all the ancestors only had a single child? So you'd be able to trace that gene back through the generations to an original and nobody else would have that gene/gene combination except one male/female ancestor, say great grandfather > grandfather > grandfather > son.

 

I think that would require marrying members of your own family, and it would have to be a father to daughter to son to daughter thing which would lead to a lot of genetic diseases.

[Mr Skeptic]

The mitochondrial DNA is passed on only* from mother to child, and the Y chromosome only* from father to son. Thus you can track anyone's maternal line, and any male's paternal line.

 

* this being biology, "only" means "only except when it doesn't"

[t-star]

Thanks for the info.

 

So... if the earth had a population of a thousand women, each with their own unique mtDNA, then if one of those women had ancestors who only ever had one female child, then that modern female child would have mtDNA that they would only share with their mother and other ancestors? So unique if all their ancestors were dead, they would be unique?

 

And mtDNA is passed to the male (but can't be passed on by the male) then a male child could also be unique in that way, only unable to pass on that unique mtDNA?

 

Is that correct?

[Mr Skeptic]

Yes.

 

(Except in reality, occasionally the sperm's mitochondria makes it into the egg, but even then is outnumbered by the mother's mitochondria, and might or might not end up in the reproductive organs. And for the Y chromosome, occasionally people get strange things like XXY or XYY or something else, so I wouldn't be surprised if somehow a Y chromosome might in very rare cases end up in a female.)

[ardent]

As for nuclear DNA, it would be impossible to pass on to your child an exact copy of a certain gene. SNPs (single nucleotide polymorphisms) are a great factor to one's unique DNA fingerprint. Also, DNA recombination between your parents during fertilization would be a strong basis of having a unique set of genes.