These changes are known as single-nucleotide polymorphisms or SNPs. These genes are sought using associations to small changes in the genes themselves and in neighboring genes. Įye color is an inherited trait influenced by more than one gene. However, OCA2 gene polymorphism, close to proximal 5′ regulatory region, explains most human eye-color variation. The genetics of eye color are so complex that almost any parent-child combination of eye colors can occur. The once-held view that blue eye color is a simple recessive trait has been shown to be incorrect. Some of the eye-color genes include OCA2 and HERC2. So far, as many as 15 genes have been associated with eye color inheritance. The genetics of eye color are complicated, and color is determined by multiple genes. Humans and other animals have many phenotypic variations in eye color. The brightly colored eyes of many bird species result from the presence of other pigments, such as pteridines, purines, and carotenoids. Eye color is thus an instance of structural color and varies depending on the lighting conditions, especially for lighter-colored eyes.

Neither blue nor green pigments are ever present in the human iris or ocular fluid. The appearance of blue, green, as well as hazel eyes results from the Rayleigh scattering of light in the stroma, a phenomenon similar to that which accounts for the blueness of the sky. In humans, the pigmentation of the iris varies from light brown to black, depending on the concentration of melanin in the iris pigment epithelium (located on the back of the iris), the melanin content within the iris stroma (located at the front of the iris), and the cellular density of the stroma. Please help to improve this page yourself if you can.Įye color is a polygenic phenotypic character determined by two distinct factors: the pigmentation of the eye's iris and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris. This article needs rewriting to enhance its relevance to psychologists.

Hazel eye color