Abstract: | Genetic and environmental influences on person-situation and person-mode of response interactions for anxiety and for dominance were investigated in an adult twin sample. For anxiety, evidence of significant genetic variance was found for the person-situation interaction and the person-mode of response interaction. For dominance, evidence of shared sibling-environmental influences was found for the person-situation interaction. Sex differences in the patterns of findings were also examined. The data indicate that the factors influencing personsituation interactions vary depending on the specific trait studied, and the results provide empirical support for the “interactionist” hypothesis that an individual's behavior can be characterized by meaningful patterns of behavior across situations. In addition, the study illustrates that behavior-genetic research can be designed to address important theoretical questions about the nature of personality. |