The main aim of the article was to show the importance of impulsivity as a background to aggressive behaviour displayed by people on the schizophrenia spectrum with particular attention to its biological determinants, including genetic ones. Imaging tests of the central nervous system allow for locating the centres responsible for particular types of impulsiveness and for modulating impulsive reactions. Excessive impulsivity may be attributed to disturbances in serotoninergic, dopaminergic, and noradrenergic neurotransmission, as well as disrupted functioning of other neurochemical pathways due to genetic alterations (COMT, Ala72Ser, Val158Met, C957T, SLC6A4). Features indicating genetic diversity have been observed among people showing different forms of increased impulsiveness: motor, cognitive and lack of planning, which can be explained at the molecular level. Predicted to be among genes that predispose to mental and neurodevelopmental disorders accompanied by intense impulsiveness contributing to aggressive behaviour include neuroligins and neurexins. The basis for such hypotheses is provided by the results of analyses conducted on animal models. It should be assumed that the results of further genetic tests in this area will allow for a more precise determination of the risk of aggression from perpetrators with psychotic disorders. This will lead to development of more effective and individualized therapeutic programmes aimed at reducing the risk of dangerous behaviour in this group of offenders, more efficient implementation of protective measures, and thus reduce costs of psychiatric treatment of insane perpetrators of prohibited acts.