Ans it only occurs in females is a wrong statement .
Colorblindness is a sex (X)linked recessive trait . Means the
defective gene will be on X chromosome .
So in females they carry two X chromosomes while males have XY
chromosomes . Females inherit one X chr from father and one from
mother . While males inherit X chr from mother and Y chr from
For a female to be colorblind both the X chromosomes need to
carry the defective allele. So if X* is the defective chromome.
Then for a female to be colorblind the genotype has to be X*X* .
Becuase if it is X*X since the condition is recessive the normal X
chr dominates and supresses the effects of the defective Chromome.
So the female becomes a carrier. That is she inherited the disorder
but is not colirblind . For a female to be coloirblind ,she must
inherit one defective X* chr from father and one X* from mother
But in males only one X chr is present and since the disorder is
X linked ,the condition gets expressed .
So males are more commonly affected . But females can also be
affected ,but the probability is lesser than males .
If this helps please give it a positive rating thank you!