Facts about your Iris

The iris of your eye is a circular membrane that can contract or expand the pupil to allow light into the eye's interior. It comes in three primary colors: blue, green, and brown, which are determined by the two genes inherited from the parents.

The iris of your eye is the circular, colored membrane that surrounds the pupil. Iris colors include brown, blue, green, hazel, and, in the case of albinos, red. The amount of melanin in the eye, the inherited genes, and the age of the person all contribute to eye color, as humans under the age of three continue to produce eye pigments.

By opening and closing the pupil, the iris controls the amount of light that enters the eye. In low light, the iris dilates the pupil, whereas in high light, the iris contracts, blocking the amount of light that enters the eye.

The iris of your eye is located behind the cornea, which is the outer layer of the eye, and in front of the lens. Humans receive two copies of the eye color gene, one from each parent. Because brown is the dominant gene, the individual may have two brown genes, or one brown gene and one blue or green gene.

Blue-eyed people can only have two copies of the blue gene, whereas green-eyed people can have two copies of the green gene or a copy of both the green and blue genes. Albinos' irises appear red because they lack melanin in their eyes.

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