Kin recognition signals in adult faces

Maloney and Dal Martello reported that similarity ratings of pairs of related and unrelated children were almost perfect predictors of the probability that those children were judged as being siblings by a second group of observers. Surprisingly, similarity ratings were poor predictors of whether a pair was same-sex or opposite- sex, suggesting that people ignore cues that are uninformative about kinship when making similarity judgments of faces. Using adult sibling faces, we find that similarity ratings for same-sex pairs were significantly higher than for opposite-sex pairs, suggesting that similarity judgments of adult faces are not entirely synonymous with kinship judgments