Immediate and sustained effects of parenting on physical aggression in Canadian children aged 6 years and younger.

Objective: To determine whether the effects of factors associated with the development of childhood (aged 6 years or younger) physical aggression were immediate (cross-sectional), sustained (longitudinal), or both.

Methods: A longitudinal subsample (n = 975) of children born between December 1994 and April 1995 was drawn from the Canadian National Longitudinal Survey of Children and Youth and followed from birth to 6 years of age. Using random- and fixed-effects logistic panel regression models, child (sex and preterm birth), maternal (education, employment, and positive or hostile/ineffective parenting), and family (lone-parent, older and younger siblings, and income) indicators were regressed on childhood physical aggression.

Results: Hostile/ineffective parenting contributed significantly to explaining the variance in aggression. At each measurement time point (birth, 2, 4, and 6 years of age), a change in hostile/ineffective parenting had an effect on aggression, and this effect carried forward across time up to 6 years. Being a boy, having a mother with less education, and living in a lone-parent family with siblings also contributed significantly to aggression. Preterm birth, maternal employment, depressive symptoms, positive interaction, and income failed to contribute significantly to aggression.

Conclusions: These results support the hypothesis that hostile/ineffective parenting has an immediate effect on aggression. Contrary to predictions that it would have an immediate effect only at the time it was occurring, hostile/ineffective parenting had a sustained effect on aggression that carried forward in time up to 6 years of age. The results suggest that hostile/ineffective parenting has an effect on aggression prior to any evidence of aggressive behaviour in the child.