Human Behavioral Genetics

Chapter 6 discusses personality genetics, a revisited "novelty-seeking gene" (DRD4), as well as two important "trait theories" of personality: Cloninger's theory and the five-factor model. The chapter provides quotes from a number of prominent researchers interviewed in recent years. Important studies on depression and on the interaction between genes and environments by Caspi and Moffitt and critiques of their "candidate gene" approach are analyzed. These interaction approaches point behavioral and psychiatric genetics both toward environmental studies, in which genetics interacts significantly with the environment over humans' lifetimes, and toward more complex strategies that can still be characterized as reductionistic. Chapter 6 closes with some sobering reflections on the difficulty of obtaining replications in an area such as human personality genetics, which some investigators still consider to be in its infancy. Some prominent researchers believe that thousands of genes are likely to influence human personality.