Question

In humans, free earlobes (E) are dominant to attached earlobes (e) and the presence of freckles (F) is dominant to the absence of freckles (f). If an individual heterozygous for both of these traits were to mate with an individual with attached earlobes and no freckles, what is the probability of having a child with attached earlobes and freckles?

Answer 1

Individual heterozygous for both of these traits has the genotype EeFf while an individual with attached earlobes and no freckles has the genotype eeff (recessive homozygous for both traits). So:

P: EeFf  x  eeff

F1: (table)

A child with attached earlobes and freckles will have eeFf genotpe from these parents, and the probability is 4/16 or 1/4 (25%).