Foundations of Behavior Genetics

Mendel’s theoretical model provided a powerful framework for understanding inheritance. However, traits that do not fit neatly into categories, but instead vary along some dimension (e.g., height), present a challenge to the Mendelian genetic model. This chapter discusses how this conundrum was resolved and how the solution led to the establishment of the field of quantitative genetics. Most behavioral traits vary along a dimension, so this issue is particularly relevant to behavior genetics. Next, the chapter introduces the concept of variance partitioning and discusses approaches commonly used in behavior genetics to investigate the roles of genetic and environmental variation on individual differences in behavior. Finally, the chapter discusses what has been one of the most important, and sometimes misunderstood, statistics in behavior genetics: heritability.