Research has already established that most of us prefer faces that are symmetrical, and probably because it is an indicator of good health. But universal standards of beauty don't go much further than that—in fact even identical twins (who have identical DNA) disagree about who is attractive, researchers report in the journal Current Biology. "We estimate that an individual's aesthetic preferences for faces agree about 50%, and disagree about 50%, with others," the project leaders from Harvard, Wellesley, and Massachusetts General Hospital write in a Eureka Alert press release. "This fits with the common intuition that on the one hand, fashion models can make a fortune with their good looks, while on the other hand, friends can endlessly debate about who is attractive and who is not." Behind the 50-50 split: Our own personal experiences seem to play a strong role in shaping our notions of beauty.
To study this, the team first tested the face preferences of more than 35,000 volunteers who visited TestMyBrain.org. They then had 547 pairs of identical twins and 214 pairs of same-sex fraternal twins rate the attractiveness of 200 faces, and deemed that experience influences one's preference for facial attractiveness more than genes. "The types of environments that are important are not those that are shared by those who grow up in the same family, but are much more subtle and individual," one researcher says. In other words, social interactions, specific media exposure, and even the faces of former lovers may impact what one finds attractive moving forward. Medical Daily reports that another study from earlier this year found that being friends first allows lovers to overlook "less desirable" physical features. (See who People calls the world's most beautiful woman.)