For some time, psychopathology researchers have attempted to disentangle genetic and environmental influences on psychopathology and to characterize the nature and magnitude of each of these influences. It is easy to lose sight of the fact that this represents considerable progress, as recognition of the contribution of behavior genetic approaches to understanding the etiology of psychopathology is a fairly recent event, and it was not that long ago that behavior genetic studies and findings were met with incredulity and opposition bordering on the fanatical. Nonetheless, the landmark adoption studies of the 1960s and 1970s, and the subsequent large-scale twin studies of the 1970s and 1980s, furnished strong evidence for substantial genetic influences on most forms of major adult psychopathology, including schizophrenia spectrum disorders (e.g., Kendler & Robinette, 1983; Kety, Rosenthal, Wender, & Schulsinger, 1968), bipolar and unipolar depression (Kendler et al., 1994; McGuffin, & Katz, 1989), and the anxiety disorders (Kendler et al., 1992a, 1992b). More recently, researchers have utilized molecular genetic approaches in a search for specific genes that contribute to the etiology of numerous forms of psychopathology. The recent sequencing of the human genome will only intensify this search, and brings with it considerable prospects and formidable problems.

In this chapter, I intend to briefly explicate a number of behavioral and molecular genetic research strategies that may aid in our understanding of the etiology and neurodevelopmental basis of psychopathology, particularly in the search for genetic influences and the characterization of these in terms of the neurodevelopmental mechanisms that they code for.