Men tend to wind up with life partners who look like their mother, while a woman is lured to a partner who looks like her father, scientists reported on Wednesday.
Heterosexuals are deeply attracted to individuals whose faces are similar to that of their opposite-sex parent, they said, suggesting that this characteristic is rooted in an evolutionary drive.
A team led by Tamas Bereczkei at the University of Pecs in Hungary created a model of facial ratios -- width of jaw, distance between mouth and brow and so on -- comprising 14 facial zones.
They measured 312 Hungarian adults from 52 different families using this method. Each family included a couple, along with two sets of parents.
The researchers found a significant correlation in facial similarities between a woman's mate and her father, and also between a man's partner and his mother.
The team tested the model on faces that were randomly selected from the general population and repeated the experiment with a panel of judges, who also picked out the same pairings from randomly selected groups of photos.
Interestingly, men and women focused on different parts of the face when they home in on a potential mate, they found.
A man's lover and his mother tended to have similar fullness in the lips, width of mouth, as well as length and width of jaw.
But for women, the critical features were the distance between mouth and brow, the height of the face, distance between the eyes and the size of a man's nose.
The choices are driven less by psychology and socialization and more by evolutionary pressures, suggests Bereczkei.
Too much genetic overlap -- as can happen with incest -- is an evolutionary no-no.
But seeking similar genetic traits "may confer individuals with additional adaptive advantages," he wrote.
It could increase the degree to which parents share genes with offspring, enhancing the genetic representation of future generations.
Finding similar partners might also help perpetuate genetic complexes that have evolved to adapt to a particular environment.
There may be an additional bonus, which probably has more to do with happiness than a genetic imperative.
"Human couples who are similar in physical and psychological characteristics are more likely to remain together than dissimilar partners, possibly leading to an increase in fertility," the study concludes.
The research appears in the journal Proceedings of the Royal Society B. The Royal Society is Britain's de-facto academy of sciences.
(Agencies via China Daily September 4, 2008)