Haemophilia is a sex-linked recessive disorder of humans. The given pedigree chart shows the inheritance of haemophilia in one family. Study the pattern of inheritance and answer the questions given.
(a) Give all the possible genotypes of the members 4, 5 and 6 in the pedigree chart. (b) A blood test shows that the individual 14 is a carrier of haemophilia. The member number 15 has recently married the member numbered 14. What is the probability that their first child will be a haemophilic male?

Explanation

(a) 4 is carrier of haemophilia `(XX^h)`
5 is haemophilic `(X^h Y)`
6 is normal (XY)
(b) The probability of the first child being haemophilic male is 25%. 50% of the first child being male and its 50% of becoming haemophilic `(XX^h xx XY)`