Basic quantitative genetic models of human behavioral variation have made clear that individual differences in behavior cannot be understood without acknowledging the importance of genetic influences. Yet these basic models estimate average, population-level genetic and environmental influences, obscuring differences that might exist within the population and masking systematic transactions between specific genetic and environmental influences. This article discusses a newer, more sophisticated and powerful quantitative genetic model that articulates these transactions. Results from this model highlight the ways in which the gene-environment interaction and correlation are intertwined. They can be used to integrate findings from quantitative and molecular genetic studies and to understand the roles of genetic influences and social forces in manifested behaviors, even when DNA sequence variation is not relevant.