The mutation was found on an entirely different gene called HERC2. HERC2 turns off OCA2, meaning it turns off the brown and reveals the blue. Every blue-eyed person has this exact same mutation.

The color of your eye is determined largely by the interaction of several genes, chief among them the OCA2 gene. The HERC2 ...

OCA2 isn’t the only gene that has a say in what color eyes you’re born with. There’s HERC2, a gene that controls how the OCA2 gene works, essentially turning P protein production on and off.