First and most importantly, of all the people living we're of ONE race, homo sapien, anything less is racist. It's really an intersting issue because it's contradictory to evolution
ALL of us have melanin, just to different degrees, so essentially we're all SHADES of the same color. As stated earlier, those who can absorb alot of sun( get darker ) also get a lot of Vitamin D (I also thought it was E also). Nonetheless, deficiencies in the vitamin have been known to lead to mental instability. Homo sapiens without melanin retain more of the Vitamins
Back the original idea of it being contradictory to evolution. . . having a lot of melanin (dark skin), dark hair, eyes, etc, are DOMINANT GENES. It's possible for two dark people to have a lighter skinned child or even one with randomly blue eyes. But the other way around is IMPOSSIBLE.
In other words, if both your parents are very pale, and you stay dark year round, congradulations, you're adopted, or someone has been sleeping. . . lol.