What decides our Eye color

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Different eye colors are more common in different parts of the world. For example in Sweden blue eyes are the most common while in China brown eyes are more common. Ireland has a relatively large percentage of green eyes. Eye color percentages and statistics can also change with time. Colors that were most common 100 years ago might be less common now.

Blue Eyes, Blue Sky
Blue eyes do not actually contain any blue pigment, rather, they appear blue for the same reason as the sky: light entering the eye is scattered through the iris, and perceived as blue because blue is the shortest wavelength of visible light, and therefore, more of it is reflected back out. So technically, the eyes themselves are not blue at all! The same applies for green, amber, hazel, and every shade in between – these are all caused by varying degrees of melanin, both in the back of the eye of the iris and the front of it, as well the structure of the collagen: finer collagen reflects more light, causing eyes to appear bluer, while coarser collagen reflects less, giving us green eyes. In people with albinism, there is no melanin whatsoever in the eye, and as such they appear red: not because they’re reflecting red light, but because we can see the blood in the eyes! This total lack of melanin also makes albino eyes highly susceptible to UV, making sunglasses a necessity outdoors.

Brown
Brown eyes are by far the most common worldwide, and in many areas of the world, such as East Asia and Sub-Saharan Africa, it’s rare to find any other colour. That’s because brown is a “dominant” gene, and so any child of both brown and non-brown eyed parents is much more likely (though not certain!) to have brown eyes too. There is no confirmed advantage of having brown eyes but research has indicated that they may be slightly better at absorbing bright light and blocking UV rays.


Changing Colours
Even if you’re born with blue, gray or green eyes, there’s no guarantee you’ll keep them throughout your life. The melanin-producing cells in your eyes may only start to become active after a few months or years, and in rare cases, even longer. When this happens, brown pigment will start to be created, leading to darker eyes.

Two Eyes, Two Colours
Heterochromia is a rare medical condition in which the two eyes are different colours. This condition is more prevalent among cats than humans, and usually consists of one blue eye and one of a darker color. Many celebrities have two eyes colors look at Kate Bosworth or Mila Kunis