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Have you ever noticed how many different eye colors there are? All these different eye colors are formed by the same pigment: melanin.

Whether you have dark or light eyes depends almost entirely on genetics. And AncestryDNA can tell you more about the role your genes play in your eye color.

Eye Colors

Eyes come in a wide range of colors, some more common than others. These colors include blue, gray, green, hazel, and all the shades of brown—some so dark they almost look black. The more melanin that you have in your eyes (specifically in the stroma, one of the layers in the colored part of your eye known as the iris), the darker your eyes are.

Melanin comes in two varieties: eumelanin and pheomelanin. Eumelanin controls black and brown colors. Pheomelanin controls red and yellow hues. It's the mix of these two types of melanin that determines whether your eye color is coffee black, honey brown, hazel, or even green, for example.

Eye Color Genetics

Eye color used to be thought of as a pretty simple trait. Brown-eyed parents, it was thought, could have kids with any eye color—although they usually had brown-eyed kids. And blue-eyed parents, it was believed, could only have children with blue eyes. In this overly simple scenario, the brown eye color was "dominant" over the blue eye color.

It turns out that in real life, the inheritance of eye color is a bit more complicated. More often than this simple model in which brown eyes are dominant might predict, blue-eyed parents can have brown-eyed kids. This is because more than one gene is involved in the eye color trait.

Genetic Markers for Eye Color

How many genes determine your eye color? There are at least a dozen eye color-related genes that scientists know of. And there are plenty more they don't know about yet.

AncestryDNA looks at four well-studied markers linked to eye color in the TYR, OCA2, and HERC2 genes, and near the SLC24A4 gene. Your pattern at these genetic markers is what determines your eye color result.

Some people have markers linked only to light eye color. Some have markers tied only to dark color. And others have a combination of both light eye color markers and dark eye color markers.

Eye Color Fun Facts

The most rare eye color in people around the world is green. The most common color is brown.

It's likely that originally all humans had brown eyes. Around 6,000 to 10,000 years ago a genetic mutation popped up in the Black Sea region that likely led to blue eyes.

Brown eyes get their color from melanin, but blue eyes don't have any blue pigment. Instead, if you have blue eyes, the front part of your eye has hardly any pigment.

Why does the lack of pigment look blue? For the same reason the sky looks blue. Particles in the rest of your eye scatter blue more than the other colors of the rainbow, making your eyes appear blue.

Curious about the link between your eye color and your DNA? Whether you have light eyes or dark eyes, an AncestryDNA test with Traits could tell you more about that connection.