Sex differences in crime are differences between men and women as the perpetrators or victims of crime. Such studies may belong to fields such as criminology (the scientific study of criminal behavior), sociobiology (which attempts to demonstrate a causal relationship between biological factors, in this case biological sex and human behaviors), or feminist studies. Despite the difficulty of interpreting them, crime statistics may provide a way to investigate such a relationship from a gender differences perspective. An observable difference in crime rates between men and women might be due to social and cultural factors, crimes going unreported, or to biological factors (for example, testosterone or sociobiological theories). Taking the nature of the crime itself into consideration may also be a factor.
Statistics have been consistent in reporting that men commit more criminal acts than women. Self-reported delinquent acts are also higher for men than women across many different actions. Burton, et al. (1998) found that low levels of self control are associated with criminal activity. Many professionals have offered explanations for this sex difference. Some differing explanations include men's evolutionary tendency toward risk and violent behavior, sex differences in activity, social support, and gender inequality.
Burton et al. (1998) assessed Gottfredson and Hirschi's (1990) "general theory of crime," which stated that individuals with lower levels of self-control are more likely to be involved in criminal behavior, in a gender-sensitive context. The purpose of their study was to account for the gender gap in crime rates. By using a self-reporting questionnaire, Burton et al. (1998) retrieved data from 555 people aged eighteen and older in the Cincinnati, Ohio, area. Early results from the study indicated that low self-control was highly positively correlated to criminal behavior in both genders, but was especially significant for males. For females, the relationship became significant when opportunity was introduced and considered with level of self-control. Opportunity was not a significant indicator of male criminal behavior, which the authors attribute to the assumption that opportunity for criminal behavior is ubiquitous for men. In this study, opportunity was measured by the number of nights per week individuals go out for recreation purposes. Similarly, the authors conclude that women are less likely to be exposed to opportunities for criminal behavior, speculating that "constraints often placed on females, and that accompany their lifestyles" contribute to less opportunity for crime. With self-control being significant for males but not for females, the conclusions of this study pointed toward the notion that men and women commit crimes for different reasons. The notion that self-control was only significant for women when combined with opportunity helps account for the gender gap seen in crime rates.