Sitting on my coffee table four piercing blue eyes caught my attention. An issue of National Geographic with Twins written in bold letters and a pair of darling girls, nose and cheeks sprinkled with freckles was on the cover. I eagerly read the article, titled A Thing or Two About Twins. Within the first few paragraphs the article mentioned that within the nature vs. nurture debate, scientists have recently discovered a third factor that plays in: epigenetics. The article talks about sets of twins that are so alike, even while being raised apart, it's astonishing. Coincidences like marrying women of the same name, having the same job, naming their children the same name, smoking the same brand of cigarettes, are things one set of twins, the famous "Jim Twins" share. 
"Twins." Jodi Cobb. National Geographic Jan. 2012. Print.
However, other sets of twins, like one pair of boys in Maryland, are very different while still sharing the same DNA and being raised by the same parents. Epigenetics seeks to explain this, the twins have the same nature, and nurture, shouldn't they be identical? Both these twins have autism, but if affects one of them much more severely, while his brother seems to be flourishing. The study of epigenetics looks into how environmental factors, like access to nutrients from the placenta during fetal development, affects the expression of genes. This can lead to twins being born at unequal birth weights, or one with a heart condition while the other is fine, as in the case of Maryland twins mentioned above. The twin who struggles more with his autism today was the one born with the heart condition, needed surgery, and was put on powerful drugs following the surgery. How those drugs affected his gene expression in his first year of life seems to have been crucial in his later development in life. Danielle Reed, a pioneering geneticist helping develop the study of epigenetics explains it like this: "What I like to say is that Mother Nature writes some things in pencil and some things in pen. Things written in pen you can't change. That's DNA. But things written in pencil you can. That's epigenetics." Miller, Peter. "Twins." National Geographic Jan. 2012. Print.
