Genetic theories of the origins of criminal behavior have been a source of contention for over a century. They have been especially controversial within the field of criminology because of the eugenic policies that they inspired that were implemented during the Nazi era. The sequencing of the human genome has created a renewed interest in the contribution of genetics to socially disapproved behavior such as addiction, mental disorders, and criminal behavior. There is fear among criminologists that information on increased genetic risks of engaging in criminal acts may adversely affect strategies used to prevent and deal with people that commit crimes. Criminal behavior is defined by statute and is necessarily a social and legal concept rather than a biological one. Some researchers have argued that criminal behaviors should be examined within the wider context of antisocial behavior. Antisocial behavior often clusters within families, suggesting that both inherited genetic factors and family environment are risk factors for this behavior. The manner in which the personality disorders and behavioral traits associated with criminal behavior are inherited has important implications for research and the potential policy uses of the research. Candidate genes are specific genes that are thought to contribute to an increased risk of engaging in antisocial behavior. Research on candidate genes for antisocial behavior has primarily focused on genes that influence the ways in which nerve impulses are transmitted and received in the brain. Three such pathways are the serotonergic pathway (impulsivity and aggression), the dopaminergic pathway (attention deficit and hyperactive disorder), and the noradrenergic pathway (anxiety and depression). It is likely that a large number of genetic variants will be identified that, in the presence of the necessary environmental factors, will increase the likelihood that some individuals develop behavioral traits that will make them more likely to engage in criminal activities. 1 table, 18 references