Can the direction of a parent/child relationship be determined from two DNA samples?

Submitted by DrOmega2468 t3_11uedet in askscience

I was listening to a podcast where they discussed finding ancient remains and DNA samples of a father/daughter pair. I was wondering, from DNA alone, is it possible to distinguish between a father/daughter vs a mother/son pair?

To my mind, one sample has half the genes of the other, But that alone wouldn't be able to determine which is the parent and which is the child, right? Maybe they had other clues to make that call? (like one was still a child?)

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babar90 t1_jctdzx5 wrote

Assuming you have the whole chromosomes genetic sequences (or long reads spanning the crossover breakpoints) yes, due to crossover with occurs during the making of gametes. So in the son there will be one of the two chromosome N (take N=2 if no crossover occured in chromosome 1..) that will be a mix of the mother's two copies of chromosome N.

On the other hand none of the mother's chromosome N will be a mix of the two copies of the son's chromosome N.

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frustrated_staff t1_jcsffpf wrote

Well....telomere length would be able to help with ages at time of death, so, if they both died in the same event, that's a pretty good indicator. Also if they were buried in the same place, geologists would be able to tell if the hole had to be re-dug or not, so there'd be some evidence one way or the other...

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