Haemophilia is caused due to the recessive, gene on X chromosome.
Y has no allele for this / if a male is XhY then he is haemophilic / if male inherits Xh from the mother he is haemophilic (with the genotype XhY).
If female inherits XhXh, one from the carrier mother and one from her haemophilic father then she can be haemophilic.
