人的眼睛的颜色 是有虹膜决定的,虹膜的颜色是由其组成的色素决定的，决定的根本是基因差异。
+ 基因一点点变异或畸变或突变 即可引起虹膜色素的变化。
这是指 同一人种的眼睛颜色不同，比如，蓝色，绿色，灰色，黄色，棕色，深棕色（黑色）等；
不是指 不同人种的眼色差异。当然不同人种的眼睛颜色也是不同的。
The color of our eyes comes from the appearance of the pigment that is present in the iris, the central part of the eye. Brown eyes are rich in melanin pigment deposits, making them darker, while blue eyes lackmelanin. Heterochromia happens when the concentration and distribution of melanin isn't uniform.
波斯猫
甚至一只眼睛的虹膜可有不同的颜色。
Heterochromia iridium (two different-colored eyes within a single individual) and
heterochromia iridis (a variety of color within a single iris) are relatively rare in humans and result from increased or decreased pigmentation of the iris. Most cases are isolated and sporadic, conceivably resulting from an alteration in the expression of the above-mentioned genes (and those we have yet to find) within the cells of the entire iris or even a particular section. Other potential causes include trauma around the time of birth or later in life, congenital pigmented nevi or even medications such as those used in the treatment of glaucoma. There are a few well-known syndromes of which heterochromia iridis is a striking feature. Waardenburg syndrome type 1, an autosomal dominant disorder caused by mutations in the PAX3 gene, is characterized by pigmentary disturbances of the iris, hair and skin, as well as congenital sensorineural hearing loss. But two different eye colors tends to be an isolated finding, which adds to the seemingly endless and fascinating variation in humans' physical characteristics.
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