#BROWN RING AROUND PUPIL HOW TO# Genes have the instructions for proteins, which do the actual work.įor example, OCA2 (the eye color gene we talked about earlier) has the instructions for making something called the P-protein. Now it isn't actually the genes that do any of this. It also takes a set of genes to tell a cell in the iris of the eye to make specific amounts of melanin. These traits come about when lots of genes work together.įor example, it takes a set of genes to instruct a cell to be a nerve cell.  Some traits are too complicated to be the result of a single gene. And one that decides whether or not you can taste a bitter chemical called PTC. So there is a gene that decides whether or not you have red hair. Each gene is made of DNA and has the instructions for some small part of you. Your genes have the instructions for making and running you. Then I'll talk about the new genes scientists found and finally I'll give a few examples of how these new genes can be involved in producing different shades of eye color. What I thought I'd do for the rest of the answer is first go through some background about genes.  Either way you end up with different shades of eye color based on the combination of genes that you have. Most likely these genes are either responsible for making melanin themselves or they control how much melanin other genes make. But given what we know about eye color, we can make some pretty good guesses about what these genes probably do. #BROWN RING AROUND PUPIL HOW TO# Scientists don't know what each of these genes exactly do and they don't know how to use them in eye color predictions just yet. This is most likely because there is more than one gene.Ī new study has identified three new genes that affect eye color. Despite some work, scientists haven't been able to find the key gene involved in green eyes. Scientists have even found the key gene, OCA2, which can explain why some people have brown eyes and some people don't. This is a common model, which you’ll find in lots of previous answers on this site, but it definitely isn’t the complete story. Scientists have a pretty good model based on two genes that can help explain blue, green, and brown eyes. What we don't have yet is a good handle on how this all happens genetically.

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