A man whose parents both have brown hair claims that his red beard was inherited from his maternal uncle. Why is this claim incorrect?
A)The Y chromosome has no role in scalp, facial, or body hair color.
B)Genetic traits are transmitted in only a direct vertical direction.
C)Females cannot transmit facial hair color to their sons.
D)Hair color is a polygenic trait, not a single-gene trait.

Question

Quizplus · Accepted Answer

Choices A, C, and D have no bearing on the correct response. Regardless of whether A, C, or D are true statements or not (hair color actually is an autosomal single-gene trait), a person can only inherit traits from his or her father and mother, not from parents' siblings. Both a person and his uncle may have inherited the same trait from a more remote common vertical ancestor (grandparent, great-grandparent) but not from horizontal ancestors (siblings, aunts, uncles, cousins).

A Man Whose Parents Both Have Brown Hair Claims That