its a known fact that because of exessive sunlight the skin comes black. But what about the penis of the man?

Question

The penis of the man dont's face any sunlight but still its black why is it so?

Answer 1

Melanin comes in two types: pheomelanin (red) and eumelanin (dark brown to nearly black). Both amount and type are determined by four to six genes which operate under incomplete dominance. One copy of each of those genes is inherited from the father and one from the mother. Each gene comes in several alleles, resulting in a great variety of different skin tones.

Answer 2

Is he by any chance of African descent? If so, it's supposed to be dark