Question

In humans hemophilia is cuased by a recessive allele on the x chromosome. Suppose a man with hemophilia has children with a healthy woman whose mother had hemophilia. What is the probability that their second child will have hemophilia?

Answer 1

probability that their second child will have hemophilia= 1/2

Step-by-step explanation:

Here, the woman had hemophilic mother (XhXh) making the woman carrier for the disease. Genotype of the woman =XhX

Genotype of hemophilic man = XhY

As per attached punnet square, out of total four children, one son and one daughter would be affected. One daughter would be normal but carrier. The other son would be normal.

Total probability of getting their second child affected with hemophilia = 1/4 daughter + 1/4 son = 1/2 (50%).