Genetics Influence Pressure to Be Thin
We know that certain genes can mean a predisposition for obesity, but a new study from Michigan State University researchers found that genes may also impact the vulnerability women feel to pressure to be thin.
To explore the role of genetic factors in whether women "buy in" to the pressure to be thin, the idealization of thinness was studied in sets of twins. More than 300 female twins from the MSU Twin Registry, ages 12-22, took part in the study. Jessica Suisman, lead author on the study and a researcher in MSU's Department of Psychology, and colleagues measured how much participants wanted to look like people from movies, TV and magazines. Once the levels of thin idealization were assessed, identical twins who share 100% of their genes were compared with fraternal twins who share 50%.
The results show that identical twins have closer levels of thin idealization than fraternal twins, which suggests a significant role for genetics. Further analysis shows that the heritability of thin idealization is 43%, meaning that almost half of the reason women differ in their idealization of thinness can be explained by differences in their genetic makeup.
In addition to the role of genes, findings showed that influences of the environment are also important. The results showed that differences between twins' environments have a greater role in the development of thin ideal internalization than wider cultural attitudes, which women throughout Western societies are exposed to.
The study, funded by the National Institute of Mental Health, appears in the International Journal of Eating Disorders