Genetics of eye color what makes blue eyes blue and brown eyes brown. and what makes people have two different colored eyes. also what make albino eyes turn red.?

Answer 1

Eye color is very complex and no one fully understands it yet. There are at least 8 gene sequences on various chromosomes that are involved somehow. But the basics boil down to the amount of melanin pigmentation in the iris.
Blue eyes contain very little pigmentation in the front of the iris so the light gets through and the shorts blue wavelengths get scattered thus making the eyes blue. Brown eyes have a lot of pigmentation and absorb most of the light before it can get scattered giving the eyes their dark appearance.
The shade of color depends on examtly how much pigment is produced. In addition, there are two types of melanin that can be produced in the eyes. One produces blue and brown shades while the other produces green and hazel shades.
Two colors of eyes are caused by a mutation that occurs in only one set of the genes changing the DNA inherited from the parents.


Albinism is a group of genetic conditions that causes a lack of pigment. It can effect only the eyes (ocular albinism) or both the eyes and skin (oculocutaneous albinism). Most types of albinism are inherited when an individual receives the albinism gene from both parents. The exception is one type of ocular albinism which is passed on from mothers to their sons.

Generally, people with albinism have blue or slate gray eyes. Some people with greater amounts of pigment have green or hazel eyes. Those with lessor amounts of pigment will have an eye color that has a reddish tint to it. Because the eye of the person with albinism has an iris which does not block out light, a flash photo of someone with albinism may show the light of the flash reflected off of the back of the eye, giving the appearance in a photograph that they have red eyes.