A pair of genetically informed studies has suggested that a child’s aggressive behaviour may drive parents to be less consistent with discipline, rather than inconsistent parenting fuelling aggression. The research, led by Joanna K. Bright of King’s College London, used data from both a large Norwegian cohort and U.S. adoption triads to investigate how parental discipline and positive parenting relate to child aggression across early childhood.
The two studies, assessing children aged roughly 4.5 to 8 years, used the same questionnaires to measure inconsistent discipline, positive parenting and child aggression. This common approach allowed the researchers to test whether the observed links held across different samples and methods.
The Norwegian analysis drew on the Mother, Father and Child Cohort Study, spanning 53,532 children born to 42,538 mothers who reported on parenting and behaviour when the child was five. By comparing families with varying genetic relatedness, including twins and their offspring, the team estimated how much of the association between parenting and aggression could be explained by shared genetics.
The U.S. dataset came from the Early Growth and Development Study and comprised 561 adoption triads — an adopted child, the adoptive parents and the birth parents. The children were adopted soon after birth and reassessed at ages 4.5, 6, 7 and 8. Because the adoptive parents and child do not share genes, their behavioural associations offer a means to explore environmental pathways without genetic confounding.
The findings point to a more nuanced relationship than a simple causal path from parenting to aggression. In the Norwegian sample, the link between inconsistent discipline and child aggression was modest. About 47% of this association was attributed to shared genetic factors, with 53% remaining after accounting for genetic transmission.
When the researchers examined this remaining relationship, the strongest evidence ran from child aggression to inconsistent maternal discipline — rather than the other way around. The best-fitting model included a pathway from child aggression to later inconsistent maternal discipline but not from discipline to subsequent aggression. The adoption study yielded a similar pattern: higher child aggression at a given age was linked to more inconsistent discipline at that age and predicted more inconsistent discipline later, while mothers’ discipline did not show a statistically significant effect on children’s aggression.
Bright and colleagues concluded that “childhood aggression drives inconsistent parenting beyond shared genetic influences.”
Sensitivity checks using fathers’ reports in the adoption study offered a somewhat different picture. When fathers reported on both parenting and child behaviour, inconsistent discipline and aggression appeared to influence each other in both directions at the same time point, though not across longer intervals. In contrast, when one parent reported aggression and the other reported parenting, no significant links emerged, suggesting that relying on a single respondent could inflate associations.
Positive parenting also yielded important insights. In the Norwegian sample, greater positive parenting correlated with lower aggression, but the researchers estimated that this association was entirely explained by shared genetic influences. In the adoption sample, the models found no evidence that positive parenting and aggression influenced each other in either direction.
The researchers noted that the findings did not differ meaningfully between boys and girls. They urged clinicians to recognise that childhood aggression can contribute to inconsistent discipline and that interventions focused solely on promoting consistent discipline may be insufficient.
Several limitations were acknowledged. The team cautioned that their questionnaires captured relatively narrow aspects of parenting and aggression, relied largely on mothers’ reports, and drew from comparatively socioeconomically advantaged families. The two samples also used somewhat different versions of the aggression measure, encompassing defiant behaviour as well as physical aggression.
The Norwegian analysis was based on data from a single time point and could not rule out the possibility that parents select partners with similar traits. The data were collected roughly a decade to two decades ago, and parenting norms may have shifted since then.
The study, titled “Triangulating evidence for genetic and environmental components of associations between parental behaviours and aggressive behaviour in children,” lists Joanna K. Bright and a team including Yasmin I. Ahmadzadeh, Olakunle Oginni, Essi Viding, Leslie D. Leve, Jenae M. Neiderhiser, Daniel S. Shaw, Misaki N. Natsuaki, Jody M. Ganiban, Eivind Ystrom and Tom A. McAdams as authors.
