The OCA2 gene (formerly called the P gene) provides instructions for producing the P protein located in the melanocytes (specialized cells that produce melanin). The OCA2 and HERC2 genes are located in this region. A region on chromosome 15 has a big part in determining eye color. Differences in the copies received from each parent causes variations in the amount of melanin produced. The chromosomes a child inherits carry genetic information that determines eye color. Eyes with no melanin on the front layer of the iris scatter light so that more blue light reflects out, so that the eyes appear blue. People with brown eyes have melanin on the back layer of the iris and some on the front layer, which absorbs more light and causes the iris to look brown. The difference in eye colors is due to the concentration and location of the brown melanin on the two layers of the iris. All eye colors have the same brown melanin incapable of refracting light. In eye color, there isn’t blue or green pigment. Genetic makeup determines the amount of melanin in the eye. How Does Your Eye Health Impact Your Life?.Learn more about the genetics of eye color, including: Although eye color is determined by genetic makeup, variations can cause different shades to appear. Know Your Health: Genetics of Eye ColorĮye colors have evolved over time and have roots in our ancestry. However, a genetic variation can cause a child’s eye color to be unpredictable, resulting in two blue-eyed parents having a brown-eyed child. With minimal levels of the same brown melanin, the eyes look blue. With high levels of brown melanin, the eyes look brown. A parent’s genetic makeup determines the amount of pigment, or melanin, in the iris of the his or her child’s eye. Whether eyes are blue or brown, eye color is determined by genetic traits handed down to children from their parents. Learn about the genetics of eye color in this guide. If blue eyes pre-dominate in Europe then brown eyes might become more desirable.Eye colors are passed down through generations, but sometimes genetic variations can lead to surprising results in eye colors. Dr Jim Wilson, chief scientific officer at the Blue Eyes Project said: "If rarity makes a feature more attractive then it could be that this process is reversed. They don't seem to sparkle."īut some believe blue eyes could one day become less desirable as they are seen as 'the norm' in Britain. Dark coloured eyes, the various shades of brown, are able to absorb longer and shorter wavelengths and therefore they appear not to reflect it. I have recently been in China and in the temples there all the gods are painted with blue eyes, but everyone else has dark eyes."Įiberg continues: "There is something attractive about blue eyes, maybe because they used to be so rare."Īlistair Moffat has another theory: "Because of the way blue eyes deal with light, they appear to have inherited a natural sparkle. One mutation 10,000 years ago has today resulted in almost 200 million pairs of blue eyes, and people with blue eyes have more blue-eyed children. Hans Eiberg, a scientist from the Univesity of Copenhagen, who made the discovery said: "Blue eyes are more attractive to potential partners than brown. The first gene mutation resulting in blue eyes is understood to have occurred in the Baltic region around 10,000 years ago. Green eyes are also a result of this change, because they arise from a combination of the blue variant with brown. Just over a third (35%) of the population of south-west England and 41% in east England have blue eyes, compared to 57% in southeast Scotland.īlue eyes are the result of a variant in the HERC2 gene, which, when it mutates, switches off the supply of brown-eye forming melanin, researchers say. The study mapped eye colour across the UK and Ireland and found that Scottish and Irish people are more likely to have blue eyes than in other parts of the UK, particularly the south. It doesn't confer any evolutionary advantage for the peacock, except that it gets him more mates." Moffat said: "It may be that all blue eyes are like the peacock's tail. He suggested one reason for their dominance is that blue eyes are recognised as being more attractive and so people seek out those with blue eyes as potential mates. Alistair Moffat, managing director of ScotlandsDNA, which carried out the research, told The Times: "A lot of people think blue eyes are much rarer than they are."
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