Identical twins are more likely than fraternal twins to hold similar views on thinness and beauty, according to the new research, published online today (Oct. 3) in the International Journal of Eating Disorders. Because siblings are raised in very similar environments, the difference between fraternal twins, who share about half of their genes, and identical twins, who share all of their genes, suggests a genetic component to what researchers call “thin-ideal internalization.”

“Thin-ideal internalization is the extent to which someone identifies with the ideal of thinness and attractiveness in our culture,” said study researcher Jessica Suisman, a doctoral student in psychology at Michigan State University. “Someone who has high levels of thin-ideal internalization would say, ‘I wish I looked more like the women I see in the media and magazines.'”