RootsChat.Com

General => Ancestral Family Tree DNA Testing => Topic started by: alicia91402 on Thursday 01 February 18 20:06 GMT (UK)

Title: Completely identical segments on chromosomes mother and child. Not half
Post by: alicia91402 on Thursday 01 February 18 20:06 GMT (UK)

I had my daughters and my own dna completed on 23andme and something odd came back. Everything is half identical like it should be except for part of a segment on chromosome 16. It is completely identical. How can that be? What does that mean?

Title: Re: Completely identical segments on chromosomes mother and child. Not half
Post by: Spike H on Thursday 01 February 18 20:45 GMT (UK)

You received a pair of each chromosome, one from each of your parents. When you pass your DNA on to your daughter each pair of yours is split and recombined into one and you give her a different set of chromosomes. Each chromosome splits at random and in up to three (maybe four) positions before it recombines. Splitting in more than three/four positions is rare. Not splitting at all and passing on a chromosomes intact is also rare.
That's what appears to have happened with you and your daughter.

Title: Re: Completely identical segments on chromosomes mother and child. Not half
Post by: alicia91402 on Thursday 01 February 18 21:03 GMT (UK)

Oh ok. That is odd. Does this have any health effects?

Title: Re: Completely identical segments on chromosomes mother and child. Not half
Post by: familydar on Thursday 01 February 18 21:16 GMT (UK)

Is it possible that your daughter's father might also match on this chromosome?  Perhaps you and he are distant cousins.

Gedmatch has an "are my parents related" tool I think, might be worth a look although I'm not sure what it requires as input(s).