text: As a child or person that has not passed through puberty the genitals are the same color as the rest of the skin on our body.  When you mature one of the first signs of adult hood is the darkening of the skin in the genital area.  So the penis skin is darker and the scrotum skin is darker than the rest of the body.  Why I don't know.  It just occurs.  I don't know why you worry about such things.