Hello, I'm an expert in the field of genetics and human eye color. Let's dive into the fascinating science behind why some people have gray eyes.

Eye color is determined by variations in a person's genes, specifically the genes responsible for producing melanin, the pigment that gives color to our eyes, hair, and skin. The amount and type of melanin present in the iris, along with the way light scatters in the iris, are the primary factors that determine eye color.

Gray eyes are a result of having a low concentration of melanin in the iris. When melanin levels are low, the scattering of light in the iris is more pronounced. This scattering effect can give the appearance of a gray or blue color, as the light is being deflected in various directions rather than being absorbed by melanin.

Another factor that can contribute to the gray appearance is the scattering of light on the front surface of the cornea. The cornea can act similarly to a prism, and with less melanin in the iris, more light is scattered, which can enhance the gray appearance.

It's important to note that eye color can change over time, especially in children. This is because melanin production can increase as a child grows, which can darken the eye color from a lighter shade to a more pigmented one.

In summary, gray eyes are caused by a combination of low melanin concentration in the iris and the way light interacts with the eye's structures.

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Remember that the blue eye color is caused by light reflecting off of the protein collagen in the stroma. You could imagine that the amount or size of the proteins in the stroma could determine how gray the eyes appear. ... One idea is that in light gray eyes, there is very little melanin on the front of the iris.read more >>