The protective role of higher intellectual functioning on violence in the household population of Great Britain

• Violence associated with below average IQ was explained by demographic factors.
• High IQ had a protective effect on all violent outcomes, except on family violence.
• Social class moderated the role of IQ on repeated and violence under intoxication.

Despite compelling evidence of the effect of intelligence on delinquency and violent crime, there is limited data on its impact on population violence. We aimed to determine the association of categories of intelligence with violent behaviors in the general population and the extent of the impact of social class on these associations. A randomly selected sample of 14,738 individuals was derived from 2 British national surveys of adults aged 16 years and older. We measured self-reported violent behavior in the past 5 years, including: repetition, injury, violence while intoxicated, familial and extra-familial victim types and intimate partner violence. We examined the moderating role of social class on all outcomes. The increased risk of violence among persons of below average IQ was explained by social class at population level. High IQ had an overall protective effect on all outcomes except violence towards family members, irrespective of socio-economic circumstances. Social class moderated the association of IQ with violence by decreasing its protective effect among those in the lowest socio-economic positions. Our findings suggest that the association of IQ and violence is not linear but protective on population level. Social class has both an explaining and a moderating role in this association.