Question

A couple has just learned that their daughter has hemophilia. they already have a son  who does not have the disease. what are the genotypes of the couple

Answer 1

If the son is normal, then he's XHY. That means that he got his Y from dad and his XH from his mother. The daughter IS hemophiliac, meaning that she's XhXh. So she must have gotten one Xh from each parent, thereby making the father XhY (he has hemophilia) and the mother XHXh (she is only a carrier).