One of my best friends back at home is the epitome of an American looking girl – blonde hair and blue eyes. Yet, something that has always mystified me is not her looks, but her parents. Her mother has jet black hair, naturally, and brown eyes. Her father also has brown eyes and brown hair. Somehow, both her and her brother ended up blonde haired and blue eyed. Was something going on here? What were the odds that not just one of them, but both of them, ended up looking so different than their parents? Being naturally nosy and curious, I looked to the internet for the answer. I knew it had to do with dominant and recessive genes, but beyond that I felt pretty uneducated. As for the blue eyes, eyes color is dictated by a pigment called melanin. Eye color is also a polygenic trait, which means there can be multiple variations of one color, or a mixture of more than one color, such as hazel. If both my friend and her brother had blue eyes, it is likely that her parents both had a recessive gene for blue eyes. There’s also the chance that one of their grandparents had blue eyes, which skipped a generation in their parents, and has now shown up in the generation of my friend. There is even the chance that my friend’s grandparents simply had the recessive gene that was then passed down to them as a recessive gene. Turns out that the likelihood that my friend and her brother would look so different than their parents is a lot more common than I thought, and considering the fact that two parents could produce 64 trillion different combinations of offspring.
Some traits don’t depend entirely on genetics, however. Weight, personality, and even height can also be manipulated by the environment. This makes sense to me, as I generally feel that my funny friends have pretty funny parents, and my heavier set friends tend to have heavy set parents. But I was confused about the height portion of this fact. I figured height was like hair color or eye color, it was something that was simply coded into your DNA and couldn’t be manipulated. This article lent me a little more information on the situation. Height is controlled by both genetics and the environment. For example, yes, you’re more likely to be tall if your father is 6’5. Where the environment comes into play is more in terms of geographic location. In countries that are poverty stricken or less developed, children are less likely to grow as much because they do not receive the proper nutrition they need to grow stronger and taller. For example, the height of an average child in the United States is likely going to be higher than a child in say, Ghana.
All in all I was pretty surprised by my findings on genetics. Who knew that something as random as crooked teeth could be inherited? As it stands, my blonde haired blue eyed friend may not be such a genetic miracle after all.
Photo Credit: http://www.everydayfamily.com/how-late-can-my-babys-eyes-change-color/