HOT moms and SEXUAL imprinting

Guys: have you got a hot mom? Chances are your wife will be a looker, too. The same goes for daughters of hunky fathers.

Women tend to date guys that look like their fathers, and sons go for gals that look like their mothers, according to a new study of facial similarities between romantic partners and their parents. The paper is published this week in the Proceedings of the Royal Society B (DOI: 10.1098/rspb.2008.1021).

Tamas Bereczkei, a biologist at the University of Pecs, Hungary, and his colleagues mapped the faces of 67 young, long-term couples at their university, as well as each parent, measuring facial proportions such as the ratios of face length to width, nose length to face height, and mouth width to height.

Based on these numbers, Bereczkei's team found that, overall, the face of a woman's boyfriend's more closely resembles her father's than the faces of other males in the study. The correlation was most striking for measurements of the centre of the face, such as the ratios between nose length to face height and eye width to face height.

Men also dated women whose faces more closely resembled their mothers than other women in the study. But here, men seemed to focus on the lower part of the face. The ratios between jaw and face width and lip fullness (height) and width of their mothers and girlfriends tended to match.

These findings hint at a process well documented in animals - and only beginning to emerge from studies of humans - called sexual imprinting. Exposure to adults can bias young animals to pick future mates that resemble their parents.

This could be evolution's way of maintaining adaptations to local environments. Mating with someone too different from you and your parents could compromise such adaptations.

On the other hand, the same process might also dissuade animals from picking mates that look too similar to their parents and even siblings to hold onto a modicum genetic diversity, which could come in handy if environmental conditions change or disease erupts. This is called optimal inbreeding.

And while studies in animals have found the same kind of opposite sex imprinting, "we do not know the precise mechanism of imprinting-like phenomenon in humans," Bereczkei says.

Ewen Callaway, online reporter