The Importance of Familial Liability for Substance Abuse and Criminality in Young Male Violent Offenders

Background: There is an interest to find out more about family background of violent offenders and how it affects the development of their problems. Aims: To investigate the association between familial liability, substance abuse disorders (SUDs) and aggressive antisocial behaviour in young violent offenders. Method: Pedigree of first, second and third degree relationship were used to measure familial liability of young, male violent offenders (n = 221) in prison. Clusters were formed based on familial liability to examine differences in amount of SUDs and antisocial aggressive behaviour. Results: Violent offenders could be differentiated into three clusters by familial liability. Familial liability had an effect on age of debut on violent crime and SUDs, life-time rates on aggression and severity of substance abuse. Conclusions: Having familial liability gives earlier age of onset and a more severe outcome regarding both aggressive antisocial behaviour and substance abuse. Some differences can also be seen between different types of familial liability. Violent crimes are a major problem in society, of both personal consequences and social costs and the World Health Organization has recognized violent crimes as a substantial public health problem (Krug, Dahlberg, Mercy, Zwi & Lozano, 2002). Violence is naturally linked to aggression and aggressive behaviour. According to Citrome and Volavka (2003) aggression is generally considered to be multi-determined. Predisposing factors for aggression include genetic factors, the fetal environment, obstetric complications, upbringing conditions, biologic factors, and psychiatric disorders like SUDs, psychosis, depression, and personality disorders. The relationshipis between violence and SUDs are well known, SUDs is clearly stated to convey an increased risk for violence and violent crime (Arseneault, Moffitt, Caspi, Taylor & Silva, 2000; Pulay et al., 2008). Both criminality and SUDs has been linked to adverse experiences in childhood and can be explained by biological, sociological and psychological theories. An earlier report on the prevalence of psychiatric problems in young violent offenders showed that they had many factors of vulnerability during childhood but also present mental illness of developmental disabilities, depression, psychosis or posttraumatic stress disorder (Billstedt & Hofvander, 2013). The majority had one or more adverse factors while growing up, such as witness and experience violence, parental alcohol or drug abuse or to be separated from family of origin. Most of the young adults had been convicted before and 84 % had substance use disorders. Although violence is a noted health problem, we still lack important knowledge about the family background of violent offenders and its significance for the development of their own problems. Therefore, there is a need to further investigate risk factors in families of violent offenders and the interactions thereof. In Sweden violent crimes constitutes over 20 % of all convictions, and even more among young offenders where they represent over 30 % of all convictions (Kriminalvården, 2014). Nine out of ten violent crimes are committed by men (Krug et