Genetic attributions and perceptions of naturalness are shaped by evaluative valence.

Genetic influences on human behavior are increasingly well understood, but laypeople may endorse genetic attributions selectively; e.g., they appear to make stronger genetic attributions for prosocial than for antisocial behavior. We explored whether this could be accounted for by the relationship of genetic attributions to perceptions of naturalness. Participants read about positively or negatively valenced traits or behaviors and rated naturalness and genetic causation. Positively valenced phenotypes were rated significantly more natural and significantly more genetically influenced than negatively valenced phenotypes, and the former asymmetry significantly mediated the latter (Experiments 1 and 2). Participants' interpretation of what "natural" meant was not synonymous with valence or genetic attributions (Experiment 3). People ascribe differing degrees of genetic influence to the same phenotype depending on whether it is expressed in socially favored or disfavored ways, potentially representing a significant threat to public understanding of genetics.