Your eyes are the windows to your soul, or so the saying goes.  But what does your eye color really say about you?  And why are your eyes colored in the first place?  As it turns out, your eyes are not only the windows to your soul, but also the windows to your genetic makeup.

Color in your iris (the colored part of the eye) is caused by a pigment known as melanin.  The quantity of melanin determines whether your eyes are dark or light.  A baby is born with almost no melanin, which is why many babies are born with blue eyes. Usually anytime between 6 to 36 months the melanocyte stroma cells start producing melanin.  Melanin concentration determines your final eye color.

So what determines the amount of melanin concentration in your eyes?  Your genes!  There's no single gene that determines the color of your eyes.  Historically it was believed that eye color was a single gene trait, but new science is showing that it's actually a multi-gene trait.  The 2 main genes responsible for eye color are OCA2, which controls almost 3/4 of the blue-brown spectrum, and HERC2, which influences the expression of the OCA2 gene.  There are other genes that contribute to eye color, and the color spectrum exists from the lightest blue to the darkest brown, and everything in between.  You get 2 copies of each eye color gene from each of your parents.  And with many people now choosing partners outside of their own ethnic group, previously rare eye colors are becoming more prominent.  In fact, studies show that due to this trend, blue eyes are becoming increasingly rare in American children over the last few decades.

Here are some additional fun facts regarding eye color:
The HERC2 gene can shut off the OCA2 gene, which results in someone having blue eyes.  Everyone with blue eyes has this anomaly.  Which means, all blue eyed people came from the same ancestor!

Some people have Heterochromia, a condition in which you have 2 different colored eyes.  This happens when your genes give you 2 different colored irises, or one iris has 2 very distinct colors instead of one.

Albino people have almost no melanin, which means their irises are clear.  However, they appear pink or red because we can see the blood vessels underneath.

Your irises can lighten or darken over time.  Your eyes do not continuously produce pigment like hair and skin do.

Only about 2% of the worlds population has green eyes.

Contrary to popular belief, it is possible for 2 brown-eyed parents to have a blue-eyed child.