Why do we have different eye colors?

Answer

Eye color is, how could it be otherwise, genetically determined. There are dozens of genes that determine eye color (>10, including OCA2, HERC2…). Some of these genes are on the sex chromosomes (the X and Y chromosome that determines whether you are male or female) and some are on the autosomes (= non-sex chromosomes).

If you look around you will see different eye colors ranging from gray, brown, green, blue, dark, light, …

The exercises in which blue and brown eye color are used and where brown is dominant are genetically incorrect, precisely because of this multitude of genes and also the resulting phenotypes = the different eye colors. Sometimes people think that you can use the eye color as a paternity test, but you better not do that.

Sometimes you also see someone with multiple colors in the same eye or simply two different eye colors, the latter is called heterochromia = “different” “color”.

Genetically you can get different eye colors because a gene on an X chromosome is switched on or off in one of the two eyes. If you start looking for photos of famous people such as Jane Seymour, Dan Ackroyd, Christopher Walken, you will find examples of them. However, the singer David Bowie had two different eye colors because one of his eyes was damaged, one of his irises was also larger as a result (the colored circle in the white of your eye is called the iris and in that iris there is a hole and this hole can change depending on the light).

Eye color, like skin color and hair color, is determined by different genes (unless, of course, you color your hair or use colored contact lenses).