A strength of Sutherland’s theory is that research supports the role of family and peer influence in criminal behaviour. Farrington et al. (2006) conducted the Cambridge Study in Delinquent Development, a longitudinal study of 411 boys from working-class backgrounds. He found that those with criminal parents or delinquent peers were more likely to offend, supporting the idea that criminal behaviour is learned through associations. However, the study is correlational, meaning it cannot establish cause and effect; other factors, such as genetics or poverty, may also contribute.