Children who experience less parental warmth and more harshness in their home environments may be more aggressive and lack empathy and a moral compass, according to a study by researchers at Michigan State University, the University of Pennsylvania, and the University of Michigan.

The study is published in the Journal of the American Academy of Child and Adolescent Psychiatry.

“The study convincingly shows that parenting—and not just genes—is associated with the development of risky callous-unemotional traits,” said S. Alexandra Burt, co-director of the MSU Twin Registry and professor in MSU’s Department of Psychology. “Because identical twins have the same DNA, we can be surer that the differences in parenting the twins received affects the development of these traits.”

In a study of 227 identical twin pairs led by Penn psychologist Rebecca Waller, the research team analyzed small differences in the parenting that each twin experienced to determine whether these differences predicted the likelihood of antisocial behaviors emerging.

They found the twin who experienced stricter or harsher treatment and less emotional warmth from parents had a greater chance of showing aggression and CU traits.

“Some of the early work on callous-unemotional traits focused on their biological bases, like genetics and the brain, making the argument that these traits develop regardless of what is happening in a child’s environment, that parenting doesn’t matter,” said Waller, an assistant professor in Penn’s Department of Psychology. “We felt there must be something we could change in the environment that might prevent a susceptible child from going down the pathway to more severe antisocial behavior.”

The work is the latest in a series of studies from Waller and colleagues using observation to assess a variety of aspects of parenting.

A subsequent adoption study, of parents and children who were not biologically related, turned up consistent results.

Waller and Burt teamed up with U-M psychologist Luke Hyde to test 6- to 11-year-old participants from a large, ongoing study of twins that Burt directs.

For 454 children (227 sets of identical twins), parents completed a 50-item questionnaire about the home environment. They also established their harshness and warmth levels by rating 24 statements such as “I often lose my temper with my child” and “My child knows I love him/her.”

The researchers assessed child behavior by asking the mother to report on 35 traits related to aggression and CU traits.

A potential next step is to turn the findings into useable interventions for families trying to prevent a child from developing such traits or to improve troubling behaviors that have already begun, the researchers said.

Though an intervention with parents could succeed, Hyde, an associate professor in Michigan’s Department of Psychology, stresses the researchers aren’t blaming parents for their child’s CU or aggressive behaviors.

“Our previous work with adopted children also showed that genes do matter, and so there is a back and forth,” he said. “Some children may be more difficult to parent. The most important message is that treatments that work with parents likely can help, even for the most at-risk children.”

—Newswise