While boys at all-male schools are more likely to go for girls with more masculine faces.
Lead researcher and psychologist Dr Tamsin Saxton in collaboration with the universities of Aberdeen, Stirling and Liverpool have, however, found the effect was weakened if children had siblings of the opposite sex at home.
During the study, the researchers recruited 240 children aged 11 to 15 at co-educational and single-sex schools to rate faces for attractiveness
The faces had been digitally manipulated to look subtly more masculine or feminine.
"Interestingly, the weakest effect of ''visual diet'' was in relation to boys'' judgments of girls'' faces," Saxton said.
"This kind of study helps researchers understand how the brain processes faces. Faces are crucial to our everyday interactions, and the brain has specialised areas dedicated to dealing with them," said Dr Anthony Little, of Stirling University.
The findings are published in the scientific journal Personality and Individual Differences.