A14: Although both biological and environmental conditions are powerful predictors of antisocial behavior and drug abuse, neither are “causal” in a deterministic sense – they are probabilistic. The intensity and frequency of exposure to negative environmental conditions, and the number and severity of internal risk factors present, determine the extent to which an individual is liable or vulnerable to behavioral disorders in general. Inherently vulnerable individuals (by virtue of their genetic make-up or biological constitution) who are subsequently exposed to an adverse environment are at imminently greater risk, particularly when adverse external influences are cumulative over time. The cumulative presence of many of these factors can result in antisocial or drug-taking behaviors (or other psychopathology) by altering brain function, disengaging coping mechanisms and compromising ability to formulate and act on rational choices.
Research in neurobiology and behavioral genetics have demonstrated that individuals vary considerably with respect to their biological strengths (protective factors) and weaknesses (risks). Biological weaknesses or vulnerabilities are influential in an individual's risk for antisocial behavior. Rather than acting alone, however, this body of research suggests that these biological features operate by setting the stage for how adaptively an individual will respond to personal stressors. A stressful environment is more likely to contribute to some form of psychopathology when it is received by a biological system that is somehow compromised. Thus, although the probability of a pathological response is a function of the number of these individual risk factors present, the probability is even greater in the presence of an adverse environment with severe