Question

Assume that human ear length is influenced by multiple genetic and environmental factors. Suppose you measured ear length on three groups of people, in which group A consists of five unrelated persons, group B consists of five siblings, and group C consists of five first cousins. With the assumption that the environment for each group is similar, which group should have the highest phenotypic variance? Explain why.

Answer 1

Group A, consisting of five unrelated persons, would exhibit the highest phenotypic variance in ear length due to greater genetic diversity from polygenic inheritance.

Step-by-step explanation:

Assuming that the environment for each group is similar, group A, which consists of five unrelated persons, should have the highest phenotypic variance in ear length. This is because unrelated individuals will have a greater genetic diversity due to polygenic inheritance, which involves many genes contributing to a trait. The variance within groups of siblings (group B) and first cousins (group C) would be lower because these individuals share a higher percentage of their genes, thus reducing the potential genetic variability of the trait within those groups. As ear length is influenced by multiple genes, siblings and first cousins will have more alleles in common compared to unrelated individuals, resulting in less phenotypic variance.