Question

In humans, the condition for normal blood clotting dominates the condition for non-clotting. These genes are sex- linked. If a male hemophiliac marries a woman who is a carrier for this trait, what are the chances that a male child will be normal for blood clotting

Answer 1

$$\def\arraystretch{1.5} \begin{array}{c:c:c} P & X^AX^a & X^aY \\ \hline F_1 & X^AX^a & X^aY \\ \hdashline F_2 & X^AX^A;X^AX^a & X^AY;X^aY \end{array}$$

The probability of giving birth to a child with hemophilia is 25%, while 50% of boys will have normal blood coagulation.