People using the dating app Tinder judge a face each time they're presented with a new dating prospect, making an instant decision about how attractive they think that person is. But while our ability (or lack thereof) to recognise human faces seems to be baked into our genetic code, when it comes to individual perceptions of beauty, personal experiences may be more significant.
That's the conclusion of a new study in Current Biology. It's not that people don't tend to agree about how attractive a face is on average: many studies have found that given the choice, people lean toward more symmetrical faces. But when Harvard University psychologist Laura Germine and her colleagues set up a citizen science project that asked people to look at photographs of faces and rate how attractive they were, they found that when they compared the data for any two individuals, their opinions on beauty agreed less than half of the time.
To see whether genetics produced those differences in people's preferences, the team repeated the experiment -- this time with pairs of identical twins and same-sex fraternal twins recruited from the Australian Twin Registry. Twin studies are a classic method of teasing out the importance of genetics to a trait: both types of twins will share more-or-less the same family environment, but identical twins share all their genes while (like any pair of siblings) fraternal twins share only 50% of them. If a trait is shared by identical twins more often than by a fraternal pair, genes probably play a big role in creating that trait.
But identical twins disagreed about the hotness of each face as much as fraternal twins did. And that suggests that the "hot or not" differences in individual preference came mostly from the sum of each person's unique experiences, rather than a genetic imperative to find a sexy mate.
So the next time you're scouting for romantic prospects on Tinder, think on that before you swipe left.
AP Photo by Tsering Topgyal