The Genetics behind Eye Colour Discovered

A recent study of 4,000 people has found that the genetics behind human eye colour is in fact controlled by many genes.

The common preconception is that each child inherits two copies of each gene, one from each parent. It has been thought that ‘brown’ was the dominant trait while ‘blue’ was the recessive trait of the eye colour gene. For a ‘recessive trait’, two copies of the gene that encodes for that trait must be present, one from both parents. However, the study has found that several genes instead of a single gene contribute to the eye colour of any individual.

A very small difference in one gene, OCA2 can account for around 74 per cent of the total variations in eye colour. The OCA2 gene produces a protein that helps give hair, skin and eyes their colour. Furthermore, small differences in another part of the OCA2 gene have also been linked to green and hazel eyes. Although it is yet to be discovered, it is believed that at least two other genes underlie these colours.

Part of the complexity is that eye colour is a continuum and not merely a trait with a few separate varieties. For this reason, it is possible for a person with not completely blue eyes and has a brown pupil ring to produce a brown-eyed child.

http://www.cosmosmagazine.com/node/1062

Rebekah Lim