From a biological point of view, your skin and hair color is 1/ 3,200,000,000th of your body’s chemistry. That’s it. We humans may think overmuch about our outsides, but on the inside our DNA is thinking, “Who cares?”

After all, you and I are built from a long chain of chemicals, half from our moms, half from our dads—the famous 3.2 billion As, Ts, Cs, and Gs that make up our DNA. We now think that the difference between being a typical Nigerian with dark skin or a typical Finn with very pale skin comes largely from a change in one pair of letters. That’s one in 3.2 billion pairs. It’s hard to believe a change that small creates such a