And not all historical non-paternity is due to marital infidelity -- it was very common for unwed young parents to have their children raised by their parents a

And not all historical non-paternity is due to marital infidelity -- it was very common for unwed young parents to have their children raised by their parents as a younger sibling. A couple raising their daughter's son as their own is Y-chromosome non-paternity despite being a direct descendant.