BackgroundHarsh parenting practices and negative parental feelings may be environmental risk factors for low self-control in children. Children may also evoke certain parenting reactions.AimsTo investigate the longitudinal relationship between parenting and self-control, as well as associated outcomes within the monozygotic (MZ) twin differences framework.MethodLongitudinal MZ twin differences analysis was conducted on a community sample of 5184 twins using data from ages 3, 4, 7 and 9 years. Outcomes related to self-control and parenting were analysed at age 12 years.ResultsNon-shared environmental effects of parenting on the development of self-control and an evocative effect of child self-control on parenting were found. Harsh parenting predicted conduct problems for both boys and girls. Self-control at age 9 predicted conduct problems and emotional difficulties at age 12.ConclusionsParenting and child self-control affect one another, highlighting the potential of early interventions that target parents and children simultaneously.