A Local Example of Human Pigmentation -- ANSWERS

        Some times, a person has inconsistent melanin production is their skin cells, their hair or
        even their eye pigments.  They will appear different from most of the population.  Some such
        people will differ but only some of the time.  Don't forget that genetics is only one of the two
        variables that determines pigmentation.  The other variable is  E N V I R O N M E N T A L   
        exposure to the sun. 

        Many years ago, a then current biology student "Bob", volunteered that he had such uneven
       pigmentation in his arms and hands as did others in his family.  It certainly sounds like this was
       a(n)  H E R E D I T A R Y  trait.  "Bob" came back to class several times over several years
       to have his arms photographed for class discussion.  Here are the results of those photos.

                 14 A

    In this photo (14A) taken during his senior year, his hands look normal.  This
    is because in  W I N T E R, he was exposed to much less  L I G H T  to trigger
    his skin cells to produce the  P I G M E N T   melanin.

               
                14 B                                14 C

     In the photo on the left (14 B) taken during the end of his sophomore year and
    the photo on the right (14 C) taken during the start of his junior year, "Bob's"
    hands appear to be blotchy in pigmentation.  This is because in both S P R I N G
    &  S U M M E R, his hands have been exposed to much  L I G H T  and only
    those regions with the  G E N E   for  M E L A N I N  production make enough
    of this chemical to tan his arms and hands.