Genes May Predispose Women To Body Image Issues And Eating Disorders

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Some women’s genes may make them more susceptible to the super-thin, airbrushed beauty ideal infused in Western culture, a new study says.

Women that are predisposed to fall prey to media representations of idealized thinness are also likely more vulnerable to eating disorders.

A team of researchers led by Michigan State University psychologist Kelly Klump interviewed 343 female twins between the ages of 12 and 22. They asked the participants to rate how much they wanted to look like people shown in magazines, TV and movies to gauge their “thin-ideal internalization.”

As the team reported in the International Journal of Eating Disorders on Wednesday, identical twins’ scores on thin-ideal internalization were closer to each other than those of fraternal twins. This suggests that there are genetic factors at play, since identical twins share 100 percent of their genes and fraternal twins share around 50 percent.

"We were surprised to find that shared environmental factors, such as exposure to the same media, did not have as big an impact as expected," lead author Jessica Suisman said in a statement on Wednesday.

"Instead, nonshared factors that make co-twins different from each other" such as participation in different sports or gravitating toward different kinds of media "had the greatest impact."

Suisman and her colleagues estimate that the heritability of thin idealization, or the degree to which individuals differed in their desire to idealize thinness can be attributed to genetics, is around 43 percent. The effects they saw were independent of the girls’ age and body-mass index.

“Interestingly, the heritability estimate of more than 40 percent is remarkably similar to the heritability of disordered eating and eating disorders and suggests that thin-ideal internalization is just as heritable as the outcomes it predicts,” the authors wrote.

Genetic factors that influence internalizing a thin ideal may overlap with heritable factors that influence personality characteristics like perfectionism.

The authors do note that it’s unclear whether their findings would be replicated in a more general population study or in populations where thinness is not held up as the Holy Grail of beauty.

But "this study reveals the need to take a similar approach to the ways in which women buy in to pressure to be thin, by considering how both genetic and environmental factors contribute to the development of thin-ideal internalization," Klump said in a statement.

SOURCE: Suisman et al. “Genetic and Environmental Influences on Thin-Ideal Internalization.” International Journal of Eating Disorders  published online 3 October 2012.

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