Question

john and pat are identical twins with identical dna. john works in a movie theater, and pat works as a lifeguard. they have very different skin pigmentation. which is the best explanation of the difference? skin color, a polygenic trait, is also determined by environmental factors. skin color, a polygenic trait, is also determined by the sex of the individual. skin color, a trait that demonstrates incomplete dominance, is also determined by environmental factors. skin color, a trait that demonstrates incomplete dominance, is also determined by the sex of the individual.

Explanation:

Skin color is a polygenic trait, meaning it is controlled by multiple genes. Identical twins have the same DNA. Since they have different skin pigmentation despite identical DNA, environmental factors play a role. Working as a lifeguard exposes Pat to more sunlight which can increase skin - pigmentation (melanin production), while working in a movie theater exposes John to less sunlight. Skin color is not determined by sex in this context, and it is a polygenic trait rather than one showing incomplete dominance in terms of the main explanation for this difference.

Answer:

Skin color, a polygenic trait, is also determined by environmental factors.