Hemophilia is defined by a recessive trait. Can a healthy man and woman have a hemophiliac son?

Let’s designate the chromosome with which the gene responsible for the development of hemophilia is linked as “Xh”, then the sex chromosome responsible for the development of the normal blood coagulation system will look like “XH”.

A child with hemophilia is XhY, and he will inherit the Xh gene from the mother, and Y from the father.

The short Y chromosome does not carry information about the blood coagulation system, so a healthy woman who can give birth to a son with hemophilia will certainly be heterozygous – XH Xh, and produce eggs: XH and Xh, the latter she will pass on to her son.