My husband who is into photography photoshopped our daughter’s eyes to green. This has ignited strings of questions from our kids. Why is your eyes light brown? Why are mine dark? How come my friend has blue, but her mom’s a bit green? What are hazel eyes? Is there Derick eyes and Summer eyes too? (My son and daughter’s respective names).
These are quite challenging questions. It has been years since I had my Genetics class. My memory has become a bit rusty. But no sweat, www.thrombocyte.com, has the answers I need.
Human Eye colors are controlled by 15 different kinds of genes which work in a rather complicated manner as oppose to Davenport’s dominant/recessive theory. This, by the way, was the explanation years back.
Today, it is said that three-fourths of brown/blue color spectrum is controlled by the gene OCA2, and a mutation in this part gives individuals very light colored eye, hair, and skin. Also, a few number of other genes like TYRP1, ASIP, ALC42A5 exert great influence on how an individual appears phenotypically. These genes work in and around the production of melanin. Melanin is a pigment present in the eyes, skin, and hair which account for the dark color of these body parts. It is located in a compartment like structures called melanosomes which in turn are capsulized in melanocytes within the iris and skin. These genes and many others work together and determine the melanin levels which give individuals a range of color from dark to hazel and to blue.
Now, this is totally Greek to my kids. So, I showed them this illustration (from the internet) and explained that light colored eyes have few, light colored melanin. While those who have very dark colored eyes have many dark colored melanin in their eyes. Liken melanin to a paint or color pencil for example.