Kelly and all... I made an error in my last post that I need to correct. In the second paragraph of my post, it should say that if the baby received an X chromosome from its father, the baby will be a FEMALE (not male as I wrote). The thing I was trying to get at is that the Y-chromosome determines maleness and because it, unlike the X chromosome, changes very little generation after generation, it is ideal for genealogical purposes. Sorry for the error. Patrick