Men like women who resemble dear old mom, and women like men who look like dear old dad, a computer analysis now shows.
Scientists in Hungary investigated 52 university students and their parents. They also looked at the significant others of the volunteers and the parents of these significant others, for 312 faces total.
The computer analysis of the volunteers' faces revealed that women often resembled their male partner's mother, a finding echoing psychoanalyst Sigmund Freud's legendary "Oedipus complex." This proved especially true when it came to aspects of the lower face, such as lips and jaws.
"Freud may be right in that a strong emotional relationship between mother and son have a strong effect on later life," said researcher Tamas Bereczkei, an evolutionary psychologist at the University of Pécs in Hungary.
There were also significant resemblances between men and their female partner's father, echoing the "Electra complex." This was especially true when it came to proportions of the center of the face, such as how far apart the eyes were or the size of the nose.
The Oedipus and Electra complexes are both named after figures in Greek myth — Oedipus unknowingly killed his father and married his mother, while Electra wanted to kill her mother, who helped plan the murder of Electra's father Agamemnon. Both complexes refer to a subconscious desire of a child for the parent of the opposite sex, often accompanied by hostility to the parent of the same sex.
Bereczkei and his colleagues suggest that people sexually "imprint" on their parents — searching, in the case of heterosexuals, for partners that resemble the parent of the opposite sex. The researchers argue that people are not merely searching for partners who look familiar, as the male volunteers did not go for female partners that resembled their fathers, and the female volunteers did not go for male partners that resembled their mothers.
The researchers conjectured the male volunteers focus on aspects of the lower face since past research suggested that area is related to how feminine women are, while the female volunteers concentrated on the center of the face of men since it sheds light on masculinity. Recent findings are uncovering how specifically faces are important when it comes to deciding mates — for instance, women seem to judge potential mates by how masculine their features are, and also seem to be able to tell which guys might be interested in becoming fathers just by looking at their faces.
Since inbreeding has both costs and benefits in terms of reproduction, the researchers conjecture sexual imprinting might have evolved to help people as a compromise to choose mates with a moderate degree of genetic similarity, who resemble one parent but not the other.
Bereczkei suggested this effect might be "even stronger between spouses belonging to different races, counterbalancing the other differences in cultural background." He also conjectured that when it comes to sexual orientation, "I expect homosexual people to behave in the same manner than heterosexuals and use parental models."
Of course, Bereczkei stressed that many factors go into choosing a mate besides the face, such as status, age and so on. "An investigation of interrelationships among these features would be a very interesting research area in future," he said. "We would like to study those specific circumstances and conditions that make similarity crucial, or at least especially important, in mating. It is possible, and our former studies suggest this, that a strong emotional bond between parent and child promotes the shaping of parental model."
To further explore their findings, Bereczkei and his colleagues plan to test volunteers with composite faces made from merging the volunteer's own face with an average face. "We wonder if these people will recognize 'their own' face and choose them as potential partner," he said.
Future research could also investigate to what degree a person's cultural background influences this effect. Another direction scientists could pursue is whether this effect is limited to mate choice, or whether it encompasses "other phenomena like friendships," Bereczkei said.