Different Colored Eyes Day is Sunday, July 12, and it's a great opportunity to learn more about this unusual phenomenon. As it grows, the human body generally follows the rule of left-right symmetry, where one half of the body mirrors the other in structure and appearance. But sometimes one eye's iris has an excess or lack of the pigment melanin, so one eye may be a different color than the other.
An inherited gene may cause this heterochromia iridum (also called heterochromia iridis). Or it may result from disease or injury. Another type of heterochromia in the eyes is sectoral heterochromia, where one part of the iris is a different color than the rest.
Many animals are prone to having different colored eyes, including certain breeds of dogs (such as Australian Shepherds and Siberian Huskies) and cats (such as Turkish Vans). Quite a few famous people reportedly have them, too, such as Kate Bosworth, Mila Kunis, Benedict Cumberbatch, Joe Pesci and Alyson Hannigan. And though we don't have a photo of Alexander the Great, he reportedly had one blue eye and one brown eye.
We don't know who came up with the idea of having a Different Colored Eyes Day, but it's a good way to celebrate the differences among us that make each living thing unique and special! Read more about eye color, as well as what causes hazel eyes and why many think green eyes are the most attractive.