160The Journal of Social Psychology, 2010, 150(2), 160–180Copyright © Taylor & Francis Group, LLCVSOC0022-4545name, Vol. 150, No. 2, 1 2009: pp. 0–0The Journal of Social PsychologyGenetic Contributions to Antisocial Personality and Behavior: A Meta-Analytic Review From an Evolutionary PerspectiveThe Journal of Social PsychologyFergusonCHRISTOPHER J. FERGUSONTexas A&M International UniversityABSTRACT. Evidence from behavioral genetics supports the conclusion that a significantamount of the variance in antisocial personality and behavior (APB) is due to geneticcontributions. Many scientific fields such as psychology, medicine, and criminal justicestruggle to incorporate this information with preexisting paradigms that focused exclu-sively on external or learned etiology of antisocial behavior. The current paper presents ameta-analytic review of behavioral genetic etiological studies of APB. Results indicatedthat 56% of the variance in APB can be explained through genetic influences, with 11%due to shared non-genetic influences, and 31% due to unique non-genetic influences. Thisdata is discussed in relation to evolutionary psychological theory.Keywords: antisocial behavior, evolution, violenceTHE DEGREE WITH WHICH ANTISOCIAL, aggressive, and violent behaviorcan be explained through evolved genetic factors continues to be debated in thesocial sciences. This paper concerns itself with identifying the degree of variancein antisocial behavior that can be explained through genetic and non-genetic fac-tors in order to better inform this debate. It is my argument that the existing“Standard Social Science Model” (SSSM; Tooby & Cosmides, 1992) has, despitevaguely acknowledging the importance of “nature” in human behavior, persistedin focusing primarily on social or environmental explanations of behavior at theexpense of genetic explanations of antisocial behavior. This may be, in part, apractical concern wherein genetics is difficult for most social scientists to con-trol. Yet this practical concern appears to filter down into theory and interventionpriorities. Ultimately, social science may be experiencing a problem related to“levels of analysis” (Tinbergen, 1963). Specifically, the SSSM, due to practicalAddress correspondence to Christopher J. Ferguson, Department of Behavioral Sciences,Texas A&M International University, 5201 University Boulevard, Laredo, TX 78041,USA; [email protected] (e-mail).Ferguson 161limitations, may have become accustomed to viewing behavior through “proxi-mal” or immediate causes or even mere correlates. For example, relationshipsbetween being abused as a child and acting violently as adults, though not alwayslarge, are commonly found in the literature (e.g. Ferguson et al., 2008). However,it remains unclear if this relationship between family violence and violent crimeis due to learning/socialization factors or genetic factors or some combination ofthe two. Specific genes or socialization influences that contribute to behaviormay be considered proximal or immediate causes of behavior. The ultimate causeof behavior, however, may more likely be the evolutionary process, whichcaused those specific genes to be selected due to specific environmental pres-sures, or which caused the ability to learn aggressive behavior to become anadaptive trait. It is the position of this article that understanding evolution as anultimate cause of antisocial behavior is an important part of the discussion onantisocial behavior and violence that, as of yet, has not received adequate atten-tion. Thus, this paper will examine the evidence for genetic contributions to anti-social behavior and explain these contributions from an evolutionary framework.The Genetics of APBIn the current article, I refer to antisocial personality and behavior (APB) asthe main variable of interest. This variable is defined as including both the innatetraits and motivation that direct individuals toward antisocial behavior (i.e., anti-social personality disorder, psychopathy) and antisocial behavior itself (i.e.,aggression, violence, lying, stealing, etc.). Use of the term APB is intended toreflect the range of dependent measures used in relevant studies, some of whichexamine personality factors (i.e., Psychopathy Checklist), and others of whichexamine behaviors (i.e., arrest records, self-reported criminal activity, etc.) Evi-dence for a genetic (or partially genetic) etiology for APB comes from two mainsources. Specifically, these are studies investigating the relationship of specificgenes and APB, and behavioral genetics research, which attempts to determinethe variance in APB that is due to genetic and non-genetic influences.Regarding specific genes, understanding of the human genome and its influ-ences on human behavior remains preliminary. However research on specificgenes in human populations has begun to provide some evidence for how genesmay contribute in the development of APB. For example, in one study of 240children with attention deficit hyperactivity disorder, children with the valine/methionine variant in the catechol O-methyltransferase (COMT) gene showedgreater antisocial behaviors than those without this variant (Thapar et al., 2005).This variant of the COMT gene also appeared to interact with neonatal risk toincrease APB. The COMT gene variant may have influenced the development ofthe prefrontal cortex, potentially reducing control over aggressive impulses.Caspi et al., (2002) used a longitudinal design to examine the impact of theMAOA gene located on the X-chromosome and its interaction with exposure to162 The Journal of Social Psychologymaltreatment in the family. Results indicated that males with both a low-MAOAactivity genotype and exposure to maltreatment were significantly more likely toexhibit child conduct disorder and adult antisocial behavior, including criminalarrests, than were high-MAOA activity genotype males who had been similarlymaltreated. Although the low-MAOA genotype on its own did not increaseAPB, it appears that its presence places individuals at risk for APB, which canbe triggered by maltreatment in the family. The presence of this gene on theX-chromosome may also help explain why males are more aggressive, on aver-age, than females, particularly if the low MAOA activity genotype is recessive innature. This finding related to the low-MAOA genotype has been replicated inother studies (e.g., Nilsson et al., 2007; Kim-Cohen et al., 2006).Retz,