Dear Student
Heamophilia is a congential diseases (hereditary diseases) which is caused by the deficiency of factor VIII, an important clotting factor. the mutation in the genome leads to this deficiency .The gene forthis factor is carried on the X-chromosome.
This gene appears in the normal (dominant) and the mutant (recessive form).You Will be knowing that females have two X chromosomes while male have only one x chromosome , so for a female to get affected by haemophilia she has to have the mutant gene on both the X chromosome while males may be affected if the carry it on the one X chromosome , Moreover haemophilia in females is lethal condition and these females may not survive past their childhood
Hope This helps you