One form of hemophilia is caused by a sex-linked recessive gene. assume that a man with hemophilia marries a phenotypically normal woman whose father had hemophilia. what is the probability that their first son will have hemophilia?

The mother inherited her father's X chromosome so her genotype is XHXh and she produces XH and Xh gametes.

The father's genotype is XhY and he produces Xh and Y gametes.

The possible outcomes are XHXh normal female (carrier), XhXh (affected female), XHY (normal son) XhY (affected son)

So the probability of an affected daugher is 1.4

When a haemophilic carrier female marries a haemiphilic man then due to ther genotypes

Xc=carrier of haemophilia

Xn=normal

Y=dont carry haemophilic genes

so here we go!

XcY cross with XcXn

genotypes of ther offsprings

1=XcXc

2=XcXn

3=XcY

4=XnY

so from whole 4 there is 50% parobability