Question

One parent (male is normal, female is carrier of haemophillic disease) , their first child is haemophillic. if their next child is male and suffers from haemophillic disease what is the probability of it

Answer 1

If the couple have son, the probability of having haemophilia will be 50%. Inheritance of haemophilia depends on the which X chromosome the child inherits. If the male child inherits the mother's normal X chromosome, the male child will not inherit haemophilia but if he inherits the mother's mutated X chromosome the child will have haemophilia.
Normal male: XY............X.............Carrier female: XX^h
Offsprings: XY, X^hY( haemophilic), XX, XX^h( carrier)