Frequency

The different forms of heterochromia also differ strongly in their frequency. A complete iris heterochromia is very rare. Because of the rarity it is very difficult to find exact details.

However, some sources indicate that a true congenital iris heterochromia without disease value occurs only in 4 out of 1 million people. The Waardenburg Syndrome, which can be a cause of iris heterochromia, occurs in one in 4500 newborns per year. With about 785,000 newborns in 2017 in Germany, statistically only 174 babies would be affected.

Other causes of iris heterochromia can be even rarer. In contrast, sectoral heterochromia is much more common. Central heterochromia is even more common.It occurs especially with light eye colors.

Is iris heterochromia inherited?

Iris heterochromia, which is not a symptom of a disease, seems to be hereditary in normal cases. Eye color is strongly controlled by genes, similar to body size or skin color. The fact that iris-heterochromia is hereditary also speaks for the fact that it can be strongly increased in certain dog or cat breeds. However, iris heterochromia can also occur in the context of different diseases. Some of these diseases occur only in the course of life and have no clear hereditary cause.

Stars and starlets with an iris heterochromia

Also with some stars one can determine an iris – heterochromia. David Bowie is often mentioned as an example. And indeed, one eye of the singer appears significantly darker than the other.

But this is not a real heterochromia. David Bowie was involved in a fight as a teenager in which one of his eyes was damaged. The consequences of this damage were visible for the rest of his life.

Well-known actors with an iris heterochromia are for example Kate Bosworth or c. Mila Kunis is said to have iris heterochromia, but it is only visible in certain pictures. Also some historical personalities are said to have different colored eyes. Alexander the Great is said to have two differently colored eyes and even rode a horse with this characteristic. However, these stories are controversial.