Beauty really is in the eye of the beholder, a "nature or nurture" study has found.
Whether or not someone is "your type" is largely the result of unique personal experiences rather than genes, researchers have said.
Scientists came to the conclusion after testing 761 identical and non-identical twins who were asked to rate the attractiveness of 200 photographed faces.
They found that only limited notions of beauty - such as symmetry - are fairly universal and may be hard-wired into our genetic make-up.
Beyond that, an individual's idea of attractiveness was shaped by that person's own unique experiences, including exposure to media images, social interactions and even the appearance of a first boyfriend or girlfriend.
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Harvard University researcher Laura Germine said: "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, potentially including things such as one's unique, highly personal experiences with friends or peers, as well as social and popular media."
Twin studies are often used to disentangle genetic and environmental influences on behaviour.
Identical twins share nearly all the same genes, so would be expected to respond the same way to purely genetic forces. Non-identical twins only share 50 per cent of their genes.
The researchers wrote in the journal Current Biology: "We estimate that an individual's aesthetic preferences for faces agree about 50 per cent, and disagree about 50 per cent, with others.
"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."
The research provided "a novel window into the evolution and architecture of the social brain", the team said.
Future studies were expected to look more closely at what aspects of the environment were most important in moulding perceptions of beauty, whether in people or art.
