Foundations of Behavior Genetics

Gregor Mendel provided the framework for understanding genetics by systematically observing phenotypes in the context of breeding experiments even though he did not understand the underlying molecular biology. His theoretical model used the abstract notion of “factors” that we have since come to call genes. Quantitative genetics extends Mendel’s theoretical model to include many genes with small effects, called polygenes, to investigate phenotypic resemblance for those with known familial relatedness. Quantitative genetics does not require knowledge of the underlying molecular processes. In this chapter, we begin to focus on the core molecular mechanisms involved in heredity. We describe the molecules of heredity, how they are passed from one generation to the next, and how they participate in a variety of biological systems and functions. By understanding genetics at the molecular level, we will be better prepared to understand the mechanisms by which familial resemblance is achieved.