Hemophilia is a sex-linked trait. A hemophilic male produces offspring with a carrier female. What are the chances that the female offspring will suffer from hemophilia? What about the male offspring? Make a Punnett square to show your work.

Hemophilia is a X-linked recessive trait. I will denote it as XA for dominant and Xa for recessive.

Hemophilic male: Xa Y

Carrier female: XA Xa

Cross:

Xa Y

XA XaXA XAY

Xa XaXa XaY

Thus, as shown, of the ratio of two possible female offspring genotypes for Hemophilia, only 1/2 will have the disease; the chance is therefore 50%.

The ratio for male offspring genotypes for Hemophilia is 1/2 as well; the chance is therefore 50%.