Chapter 6 provides us with an introduction to research and theory at the interface of genetics and personality. The authors begin with a discussion of the human genome, then move to a consideration of the controversy surrounding genetic influences on personality. The authors note that much of this controversy is generated by misinformed political and ideological concerns about the application of the findings from behavioral genetics.

Next, the authors review the scholarly goals of modern behavioral geneticists, and then provide a definition for key terms such as heritability, environmentality, phenotypic variance, and genotypic variance. The authors detail several key misconceptions about heritability, including that it can be applied to a single individual, that it is constant and unchangeable, and that it is precise.

The authors then review the four key research designs used by behavioral geneticists, including the selective breeding design, family designs, twin designs, and adoption designs. Each design has advantages and disadvantages, and these are reviewed in turn.

Next the authors review the major findings generated from behavior genetics research, including findings in the areas of traditional personality traits, sexual orientation, attitudes and preferences, drinking, and smoking. The authors then discuss and differentiate shared and nonshared environmental influences. Next the authors review work on genotype-environment interaction and correlations and then address recent work in the new area of molecular behavior genetics.

The authors close with a discussion of the inter-relationships among science, politics, and values.