What is it called when a person has two different colored eyes?

Question

and what causes it?

Answer 1

It's called heterochromia and it is generally just inherited, when a person has "an excess or lack of melanin (a pigment)"

Answer 2

Heterochromia iridium is the official name used to describe this condition. It occurs when a person has different levels of melanin in their irises which can result from a genetic mutation or as a side effect to an environmental condition.

Answer 3

Eye colour is determined by Melanin a dark brown pigment in the iris. Blue eyes are due to a lack of Melanin. When you have differing amounts of Melanin in each iris your eyes become different colours. It is called Heterochromia Iridium or Pie Eyed.

Answer 4

It's called heterochromia and it's caused by excess melanin in one eye. Melanin is the chemical that gives I and skin pigmentation.