Question

Hemophilia is caused by several genetic factors; one, a recessive allele of an x- linked gene, is the subject of this problem. assume that a man with hemophilia marries a normal woman whose father had hemophilia. what is the probability that their first son will have hemophilia?

Answer 1

50%.
First off, XhY means hemophilia for a male. The father has hemophilia, making him XhY. The mother doesn't have it, but must be a carrier because her father had it. This makes her XHXh.
Sons only receive a Y from their father, and either X from their mother. So theirs sons will either be XHY (normal) or XhY (hemophiliac).

Answer 2

It’s recessive. The mother who is a carrier is heterozygous, but she does not have the disease. The only offspring who have the disease are the boys who inherited one mutated gene.