Heterochromia iridum

Even if you don’t recognize the name, you probably know this phenomenon from seeing a Siberian Husky. These pets often have one blue eye and one brown eye! It also occurs in cats and other animals, as well as in humans. 

The most common reason is the difference in production, final concentration or supply of the pigment melanin to the iris of the eye, resulting in mosaicism or chimerism. Some scientists also point out the possible role of epigenetics in the creation of this phenomenon – but as you know, epigenetics can be used to explain almost everything;) 

Interesting fact: According to historical sources, Alexander the Great had heterochromia iridium.