If a man and a woman, both having normal color vision (colorblindness is X-linked recessive) have a daughter that is colorblind, which of the following is most likely true?
(hint: this one has a bit of a trick to it)
A: both man and woman are carriers (heterozygous)
B: man is a carrier of colorblindness but the woman is homozygous normal
C: Mom is a carrier but the father has to have been colorblind; the man in this is not the girls father, or there was a mixup at the hospital, or a mutation has occurred.
D: the daughter must be hterozygous for colorblindness

Question

If a man and a woman, both having normal color vision (colorblindness is X-linked recessive) have a daughter that is colorblind, which of the following is most likely true?
(hint: this one has a bit of a trick to it)
A: both man and woman are carriers (heterozygous)
B: man is a carrier of colorblindness but the woman is homozygous normal
C: Mom is a carrier but the father has to have been colorblind; the man in this is not the girls father, or there was a mixup at the hospital, or a mutation has occurred.
D: the daughter must be hterozygous for colorblindness

anonymous · Answer

i would say C only because it said that X is recessive and a female is XX while a male is XY. i'm not 100% sure that the answer is C though.

anonymous · Answer

I would say C also.  
Men have only 1 X chromosome, meaning that if he 'carried' it he would also have to be colorblind.  So that rules out A and B as the man is stated earlier to not be colorblind.
If the daughter was heterozygous for colorblindness, she would not express the gene; only carry it because girls have 2 X chromosomes.