Twins show genes may play a role in body image
POSTED: Thursday, October 4, 2012 - 9:00am
UPDATED: Thursday, October 4, 2012 - 9:04am
CNN — Blame for a teen's unhealthy body image often falls on the media. The barrage of size-zero supermodels and waif-like celebrities walking the red carpet could push anyone to curse their shape, right?
A study published this week in the International Journal of Eating Disorders finds a new culprit may also be partially to blame: Our genes.
Researchers wondered why only a small percentage of the population developed an eating disorder when everyone was being exposed to the same images. They hypothesized that certain genes could make a person more or less prone to accepting the "thin ideal."
Lead author Jessica Suisman, a clinical psychology graduate student at Michigan State University, and her colleagues analyzed data from 343 female twins aged 12 to 22 years old.
More than half of the twins were identical; 138 were fraternal. Identical twins share all of their genes, while fraternal twins only share 50 percent.
Each twin was asked nine questions from a standard body image questionnaire that determined the degree to which they wanted to look like various media personalities.
The researchers also examined the environmental factors that the twins shared (their parents, their school) and the factors they didn't share (different friend groups, extracurricular activities, etc).
Identical twins were significantly more likely to have similar scores on the questionnaire than fraternal twins, suggesting genetics play a role in determining whether or not we will strive to look like the celebrities we admire.
"This sort of design doesn't tell us which genes (are involved)," Suisman said. "We do know that there isn't a single gene for thin-ideal internalization. It's small effects from numerous genes."
The researchers also found that shared environmental factors had little influence on the twins. In other words, sharing a house didn't mean the twins would have similar views on body image.
Suisman hopes to take a closer look in the future at what might be "underpinning" the genetic effects they found.
Personality traits are often decided by genes, she says, and may play a part in determining who's more likely to develop an eating disorder. For instance, other studies have suggested perfectionism could lead to an unhealthy body image.