The researchers sought out to measure to what degree women bought into the perceived ideal of thinness, which the researchers call thin-ideal internalization. With this is in mind, scientists at Michigan State University, performed tests for 300 female twins aged between 12 and 22. An assessment of how much participants wanted to look like people from movies, TV and magazines was made, after which a comparison was made between identical twins who share 100 percent of their genes and fraternal twins who share 50 percent. It was found that identical twins have closer levels of thin idealization than fraternal twins, implying genetics had a significant contribution.
Upon a closer look, the researchers were surprised to find that the heritability of thin idealization is 43 percent, meaning that almost half of the reason women differ in their idealization of thinness can be explained by differences in their genetic makeup. Thus, the study shows that media exposure to idealized body size has a less significant role to play than previously thought.
“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,” said Jessica Suisman, lead author of the study. “Instead, non-shared factors that make co-twins different from each other had the greatest impact.”
“The broad cultural risk factors that we thought were most influential in the development of thin-ideal internalization are not as important as genetic risk and environmental risk factors that are specific and unique to each twin,” she concluded.
The study, funded by the National Institute of Mental Health, appears in the International Journal of Eating Disorders.
source MSU