Are babies' faces cues to their parents' fitness?

Most adults prefer attractive individuals and treat them more favorably. It has been proposed that this bias is adaptive for choosing high-quality mates because attractive individuals are more likely to carry fitness-enhancing genes. If offspring can inherit fitness-enhancing genes, the offspring's attractiveness might serve as an additional cue for assessing a parent's genotypic quality. The authors tested this possibility by asking women and men to rate the facial attractiveness of adults identified as parents whose faces were shown alone or with a child (identified as either their own child or an adopted child). For women, the authors found that offspring attractiveness was used to adjust judgments of a parent's attractiveness and that this effect was most evident for adult-infant pairs identified as biologically related. For men, the authors found that infants, independent of their attractiveness, adjusted judgments of a parent's attractiveness, and this effect changed depending on the sex of the adult face as well as the biological relationship between the adult and the infant. These findings are consistent with the hypothesis that an infant's appearance is a cue to important information about the parent's fitness and thus prompt new questions about how one's kin may be used in judging attractiveness.