That, apparently, is the gist of recent studies from NYU and Princeton. From the Daily Mail (UK):
Two groups of men and women were shown a selection of thousands of computer-generated faces of the opposite sex to rate, which had been manipulated to look either more masculine or feminine
The computer model tested 50 dimensions of facial features, including nose size, plumpness of lips and facial colouring.
The scientists found that more men want women’s faces to have a feminine shape, while women want men’s faces to have a feminine shape, but darker skin.
All of this seems to explain Zac Efron. But it also says something odd about contemporary tastes.