When you’re pregnant, running genetic tests that do things like calculate the possible color of your future child’s eyes is a wonderfully fun thing to do. My first stop when I wanted to see what the most likely color of our son’s eyes would be was an eye color generator that I found online. It’s worth bearing in mind that these calculators are based on two gene models, and will never be 100% accurate. Even today, scientists aren’t completely sure about just why we end up with the color of eyes that we have. There are models around for brown, blue and green eyes, but nobody is entirely sure about grey, hazel or violet eyes. So do bear that in mind when you’re playing around with genetic calculators.
In my case, my husband has very dark brown eyes while I have blue. On genetic websites I was asked to list what color our eyes were as well as that of both our parents. My husband’s father has brown eyes and his mother has hazel eyes. As there were only options for brown, blue or green I chose green rather than hazel. And the same went with my parents. My mother has blue eyes and my father has hazel (or green as I put). According to the eye calculator, my son had only a 20% chance of coming out with blue eyes, just below a 30% chance of green eyes and a 50% chance of having blue eyes. Result? My son has blue eyes. So while the odds may have seemed against it, it still happened.
Why did my son end up with blue eyes though over brown eyes as my husband has brown eyes and brown is meant to be the dominant gene – over both green and blue eyes with blue eyes being recessive? Well, I have blue eyes and could only have passed two blue-eyed genes on to our son as those who are blue-eyed can only pass on blue-eyed genes. The deciding factor in the case of my husband and I rested with my husband.
If my husband had passed two brown-eyed genes to our son, he would have brown eyes. He would still have had brown eyes even if my husband had passed on one brown-eyed gene and one blue-eyed gene. But because my husband passed on two blue-eyed genes (and they have to be two as blue is a recessive gene) our son ended up with blue eyes. The only reason my husband even carries these genes is due to a great grandmother in his family who once had blue eyes – the only one what we know of as he is Turkish. So in the end, it was my husband who had the genes that allowed our son to have blue eyes.
Sources: http://discovermagazine.com/2007/mar/eye-color-explained
http://www.sewanee.edu/chem/chem&art;/Detail_Pages/ColorProjects_2003/Guttery/index.htm
http://news.bbc.co.uk/1/hi/sci/tech/6195091.stm
http://genetics.thetech.org/online-exhibits/what-color-eyes-will-your-children-have
