We're cousins -- if you have blue eyes.

If you have blue eyes, you and I are probably cousins.

Yeah. I know. The cousin part is really -- a "closer cousin." Since, if you are human -- we are cousins. Most of you reading this are human, right? Other than a spider or an AI program -- you're human. . .so we are cousins. . .

Research geneticists have discovered the genetic switch that turns your brown eyes -- blue. Your close relationship to me (with blue eyes) stems from a likely single ancestor bearing the mutation from 6,000 to 10,000 years ago. Involved is the OCA2 gene that seems to be related in several eye colors, with mutations leading to green and hazel eyes. This gene is involved in melanin production which also colors hair and skin.

I think this is a woman's blue eye.
Image: Wikipedia

Researchers examined the OCA2 gene and never found the blue-eyed gene, because they were looking in the wrong place. They had looked for the switch in OCA2 for a long time -- and the switch is the key. The actual "switch" control over blue eyes is the rare case of one gene regulating another, and the switch is on nearby gene HERC2.

http://sciencenow.sciencemag.org/cgi/content/full/2008/201/1

Geneticists say there are 10 ways to get red hair -- but only one way to get blue eyes.

If you have blue eyes, we probably had a mutant mother from somewhere in the Black Sea part of the world who migrated to Northern Europe from 6,000 to ten thousand years ago.

Why did this recessive characteristic persist?

Girls, do you like them blue-eyed boys?

Tell us.