Attractive couples hand their good looks down to their daughters, but have little impact on whether their sons are handsome, according to a new study.
University of St Andrews boffins have found that while both parents influence the attractiveness of their daughters, male attractiveness is not inherited.
In a study of family photographs, psychologists Professor David Perrett and Elisabeth Cornwell - now at the University of Colorado - found that while both father and mother can influence the attractiveness of their daughters, the couple's good looks do not necessarily contribute to the attractiveness of their son as an adult.
The researchers studied the family photo albums of students, collecting images of over 100 females and 100 males and their respective biological parents taken over several years.
The photos of each student, father and mother were rated separately for attractiveness, and for femininity/masculinity.
They found evidence that attractiveness passed from both father and mother to daughter, and also that attractive fathers were more likely to produce attractive, feminine daughters, whether the mother was attractive or not.
When we looked at women's faces, we found clear evidence that attractiveness passed from both father and mother to daughter, said the professor.
We are perplexed as to why we did not find any evidence for the inheritance of attractiveness in males, through either the female or male parent, the expert added.
The survey found men with strong masculine traits are likely to produce similarly macho sons, but macho sons are not considered especially attractive.
Some believe females can increase their reproductive success by choosing sexy mates, whose genes are passed on to male offspring, making them attractive to females.
The hypothesis presumes that masculinity underlies male allure. However, the research at St Andrews contradicts this and found that attractive fathers and mothers do not necessarily produce facially attractive sons.
We checked to see if male and female facial traits are inherited, he added.
The research is published in the journal Animal Behaviour.