Socio-Genetics seeks to understand both the genetic and environmental contributions to individual variations in behavior. Behaviors, like all complex traits, involve multiple genes, a reality that complicates the search for genetic contributions. As with much other research in genetics, studies of genes and behavior require analysis of families and populations for comparison of those who have the trait in question with those who do not. The result commonly is a statement of "heritability," a statistical construct that estimates the amount of variation in a population that is...