In regard to the baby's colorblindness, a sex-linked recessive trait, you explain that
A) colorblindness often appears randomly, even if neither parent is colorblind.
B) the baby's father must have a recessive allele for colorblindness.
C) since colorblindness is sex-linked, a son can inherit colorblindness if his mother has the recessive colorblindness allele.
D) the eggs must have been accidentally switched, since males inherit sex-linked traits only from their fathers.

Question

Quizplus · Accepted Answer

Colorblindness is a sex-linked recessive trait that is carried on the X chromosome. Since males have only one X chromosome, they will express the trait if they inherit the recessive allele from their mother. Therefore, a son can inherit colorblindness if his mother has the recessive colorblindness allele. The father's carrier status is also important since he can pass the allele to his daughters. Option A is incorrect because even if neither parent is colorblind, they could still be carriers of the recessive allele. Option D is incorrect because sex-linked traits are inherited from both parents, but males express the trait differently due to having only one X chromosome.

In Regard to the Baby's Colorblindness, a Sex-Linked Recessive Trait