The idea of individual responsibility for action is central to our conception of what it is to be a person. Behavioural genetic research may seem to call into question the idea of individual responsibility with possible implications for the criminal justice system. These implications will depend on the understandings of the various agencies and professional groups involved in responding to violent and anti-social behaviour, and, the result of negotiations between them over resulting practice. The paper considers two kinds of approaches to the question of responsibility and ‘criminal genes’ arising from a sociological and philosophical perspective respectively. One is to consider the social context and possible practical implications of research into ‘criminal genes’ which will later be examined through interviews and discussions with a range of experts including lawyers and social workers. A second and different kind of approach is to ask whether the findings of behavioural genetics ought to have implications for attributions of responsibility. Issues of genetic influence are central to both approaches.