Genetic and Epigenetic Models

Both genetic variation and environmental exposures play key roles in the development of mental health or psychopathology. Their roles are interdependent: The effects of genetic variants depend on environment, and the impact of environment depends on the genetic variants. This chapter will explain and critically review the most important models of gene–environment interplay, including gene–environment correlation, gene–environment interaction, and epigenetics. Gene–environment correlation describes a mechanism where genetic variants influence the likelihood of environmental exposure. Gene–environment interactions refer to a mechanism where genetic variants influence the impact of an environmental exposure on the individual. Finally, epigenetics provides a molecular mechanism through which environmental exposures affect the function of genes for long periods of time. The chapter concludes with a discussion of the limits of current knowledge, its implications for treatment and prevention, and directions for further research.