National Geographic: Studying Twins Could Reveal A Lot About All of Us
My twin sister and I (left) are polar opposites: She’s great at science and math, I’m terrible at both. I live in New York City, she lives in a Midwestern suburb. I’m a night owl, she’s a morning person. And so on. But despite our differences, we know for certain that we’re identical twins. We were born at 28 weeks, an incredibly early gestational age even for twins, with Twin to Twin Transfusion Syndrome, a disease of the placenta that affects only identical twin pregnancies. As a result of the syndrome, I was born at 3 lbs, 12 ozs, with most of the blood; my sister was born at 2 lbs, 12 ozs, with virtually none. After Erin received blood transfusions and we spent 8 and 6 weeks, respectively, in the NICU, we went home without any lasting ill effects from the syndrome.
Our parents, friends, and even strangers have spent a lot of time analyzing how my sister and I differ, and if you’re a twin you know that these comparisons are humorous at best and intrusive at worst. But as it turns out, there’s good reason for scientists to explore how identical twins differ. In “A Thing or Two About Twins,” which appears in this month’s National Geographic magazine, writer Peter Miller offers an in-depth look at how studies of twins can help scientists “untangle the influence of genes and the environment.”
“Because identical twins come from a single fertilized egg that splits in two, they share virtually the same genetic code. Any differences between them—one twin having younger looking skin, for example—must be due to environmental factors such as less time spent in the sun.
Alternatively, by comparing the experiences of identical twins with those of fraternal twins, who come from separate eggs and share on average half their DNA, researchers can quantify the extent to which our genes affect our lives. If identical twins are more similar to each other with respect to an ailment than fraternal twins are, then vulnerability to the disease must be rooted at least in part in heredity.”
It’s a fascinating read and the portraits of twins by photographer Martin Schoeller are stunning–take a look if you have a minute. (Full disclosure: I was an editor at National Geographic Traveler for nearly 6 years, but I don’t know the author of this article.)
Are you a twin, or the parent of twins? Share how you and your twin (or how your twins) differ here!