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?

Answer 1

And melanin is produced by the body. The amount created is not entirely genetic, but instead dependent on the amount of sunlight received

Answer 2

John and Pat's occupation best explains the difference between their skin pigmentation. Since Pat works as a lifeguard, she is more exposed to the sun, which tans her skin. John, on the other hand, works in the theater, where he isn't exposed to sunlight that much, so he is much lighter than his twin, Pat.