Look closely at your eyes in the mirror. You might see streaks of chestnut brown, ocean blue, or forest green in your iris, the colorful part of your eye. Have you ever wondered why people have different-colored eyes?
Eye color comes from melanin, the same substance that gives our skin and hair their special shades of color. The iris is made up of two layers. In almost every eye, the cells that make up the back layer have a brown color. In brown eyes, some cells in the front layer of the iris also have melanin. The more melanin, the darker the eye! In blue eyes, there is no melanin at all in this front layer. If your eyes are green or hazel, this layer likely has a bit of melanin that causes your eye to appear not quite brown but not quite blue.
Eye color is an inherited trait. That’s a characteristic passed down from generation to generation in your biological family. Information from your parents’ cells combined to tell your eye cells how much melanin to produce. Because of how eye color is inherited, you may not have the same eye color as your parents. But if both of your parents have the same eye color, you’re likely to have it too!
Everyone’s eye color is unique. “You and a family member may share the same color eyes,” says Shivani Kamat, an eye doctor in Texas, “but how much melanin is in your iris and how it is spread out is special to each person.”