Men with feminine faces will be luckier in love as most women are attracted to them rather than masculine men, Liverpool University scientists say.
Image of Tom Cruise, altered to look more feminine on the left and masculine on the right
While square-jawed men attract beautiful women, the less macho ones have a wider choice as their face type is more in demand.
Most women like a feminised face, but those who rated themselves attractive went for the classic masculine face.
Feminine faces tend to be linked with stability and caring, scientists said.
Several hundred students and staff at the university were shown a selection of computer-generated faces, manipulated to look either more masculine or feminine.
They were asked to judge what facial type they were most attracted to.
Image of Julia Roberts, altered to look more feminine on the left and more masculine on the right
"Facial types indicate how a particular person might behave in a relationship and the potential benefits they could give to offspring," said Dr Tony Little, from the University of Liverpool's School of Biological Sciences.
"A masculine face is linked to high testosterone levels, which demonstrates good genetic qualities.
"Those women who prefer masculine men are selecting genetic benefits for their children, despite the fact that high testosterone levels can also increase the likelihood that the male will have an affair.
"Those men with a feminine face tend to be associated with stability and caring," he added.
Women who considered themselves highly attractive were more willing to take a risk with a highly testosterone-charged male, and were less likely to fear such a man straying.
A second study showed that women seen with a dominant male were rated more attractive by other men.
The male volunteers were shown pictures of fictitious couples and asked to rate the male's dominance in relation to themselves and how attractive they found the female.
Men who rated themselves as attractive preferred women with feminine facial features, such as a small nose and chin and large eyes, which are indicators of fertility.
Dr Little said: "A man who feels that he has something beneficial to offer in a relationship, will want something in return and therefore will choose a partner who can transfer his genes to offspring successfully.
"We have also found that people tend to be attracted to those who look similar to their opposite-sex parent.
"Your choice of partner would therefore look similar to you, thus increasing the chances of your children also resembling you."
The public can participate in the study at Liverpool University through the website www.alittlelab.com.
The researchers want to explore how faces influence the success or failure of relationships.
Study data will also be used to determine which facial types are likely to promote feelings of jealousy.