By Christian Jarrett

In our culture we like to speculate about the effects of different parenting styles on children. A lot of this debate is wasted breath. Twin studies – that compare similarities in outcomes between genetically identical and non-identical twins raised by their biological or adopted parents – have already shown us that parental influence is far more modest than we usually assume. Now a paper in Social Psychological and Personality Science goes further, using the twin approach to reveal how it is mistaken to see the parent-child dynamic as a one-way relationship. “Given the current evidence … it is more accurate to conceptualise parenting as a transactional process in which both parents and children exert simultaneous and continuous influence on each other,” write Mona Ayoub at the University of Illinois at Urbana-Champaign and her colleagues.

Ayoub’s team used data from the Texas Twin Project, including parents’ ratings of their parenting style (specifically, their warmth and stress levels in relation to each child), and the children’s ratings of their own personality traits based on a kids’ version of the Big Five personality test. In all there were 497 identical twin pairs in the study, 480 same-sex non-identical twin pairs, and 434 opposite-sex twins, and their average age was 13.

The logic underlying the researchers’ approach was that if children affect their parents’ parenting style via their own gene-linked traits, then, on average, the parenting style towards each twin in a pair of identical twins should be more similar than the parenting style towards each twin in a pair of non-identical twins.

That’s exactly what the researchers found. Twenty-seven per cent of the variance in parents’ levels of warmth, and forty-five per cent of the variance in their parental stress levels, was attributable to genetic influences originating in their children. A significant portion of this genetic influence was related to the children’s personality traits: kids who scored higher on agreeableness and conscientiousness tended to have parents who parented with greater warmth, and kids with lower agreeableness had parents who parented with more stress.

The data back up what many mothers and fathers already know through experience – being a paragon of patient parenting is not much effort when your little darling is an angel, it is much trickier when they are a brat.

The children’s personality traits explained about half of the association between children’s genes and their parents’ behaviour, suggesting other gene-linked traits in the children also have an influence, such as, the researchers suggested, depression and “externalising behaviours”, which means things like aggression and disobedience.

The study was also able to look for the influence of non-shared environmental factors on the parents’ behaviour and the children’s personality traits – these are environmental (non-gene linked) factors that affect one twin but not the other, contributing to different parenting styles toward each twin in the same family. The data can’t specify what these factors are, but an illness that affects one twin but not the other would be an example.

Though less significant than children’s genetic effects, the researchers found that non-shared environmental factors both increased parents’ stress levels and reduced children’s conscientiousness and emotional stability (it’s not clear if such environmental factors affect parental stress, which then has an adverse effect on their children’s personality, or vice versa, or both).

Ayoub and her colleagues highlighted the practical implications of their findings: “parenting interventions may be more efficacious if both parents and children are treated, such that the intervention is tailored to the unique qualities of both parties.”

A limitation of the study is that it only provides a snapshot of the dynamics between parents and children. It’s likely that the effect of children’s personalities on their parents’ nurturing style is just one aspect of an unfolding dynamic, as parenting style then feeds back and affects the child (albeit more modestly than we often assume). “Longitudinal designs that assess child personality and parenting throughout development will be useful,” the researchers said, “especially because parenting can take different meanings across different developmental stages.”

—Genetic and Environmental Associations Between Child Personality and Parenting

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest