- Joined
- Oct 1, 2017
Eye color turned out to be a lot more genetically complex than once thought. Up until a few decades ago, it was taught that each parent contributed a single gene for eye color and since one was usually dominant and one recessive, it was believed that predicting the outcome of what eye color a person might have was fairly straightforward. For example, Brown eyed genes were dominant and blue eyed genes were recessive. A parent with brown eyes might have one brown eyed gene and one blue eyed gene and if they contributed their brown eyed gene to their child, then that child would have brown eyes, regardless of what gene the other parent contributed. If the brown eyed parent contributed a blue eyed gene and the other parent also contributed a blue eyed gene, either because they had blue eyes themselves and therefor no other gene to contribute or were a brown eyed hybrid like their partner, then the child would have two blue eyed genes, which meant their eyes would be blue.
However, as scientists further studied genetics and the human genome was mapped, researchers realized that eye color was a lot more complex than they had first thought. While certain genes are still considered to be dominant over others, it turns out that there are many genes that contribute to eye color, not just one, or one per parent. This means that no matter what eye color two people have, they could potentially have offspring with a myriad of possible eye colors.
To date the genes that are known or thought to contribute to eye color are ASIP, IRF4, SLC24A4, SLC24A5, SLC45A2, TPCN2, TYR, and TYRP1, which are believed to combine with OCA2 and HERC2 to produce an extremely wide spectrum of human eye colors.
