If a woman has hemophilia and marries a man who does not have hemophilia, she will have a 25% chance of having a son with hemophilia, a 25% chance of having a daughter with hemophilia, a 25% chance of having a son without hemophilia and a 25% chance of having a daughter without hemophilia.
This is due to hemophilia being conditioned by the recessive gene "h", carriers of the "H" gene do not have the disease. Thus, a woman with the disease would have the [tex]X^{H} X^{h}[/tex] genes, while a man without the disease would have the [tex]X^{H} Y^{H}[/tex] genes. The cross between these two would be [tex]X^{H} X^{h}[/tex] x [tex]X^{H} Y^{H}[/tex] = [tex]X^{H} X^{H}[/tex](daughter without hemophilia), [tex]X^{H} X^{h}[/tex] (daughter with hemophilia), [tex]X^{H} Y^{H}[/tex] (son without hemophilia), [tex]X^{h} Y^{H}[/tex] (son with hemophilia).
