Nature and nurture both matter for children's early behavior problems
Parents often worry about whether their child's early behavior is just the "terrible twos" or behavior that will escalate to aggression, stealing, and fighting over time.
Most children grow out of the terrible twos to become well-adjusted. However, research has shown that most career criminals started their antisocial behavior during the toddler years.
Now a team of researchers from Penn State and seven other universities has discovered new clues identifying which children may be at risk for the worst antisocial outcomes and the source of these early problems.
The findings appear online today (April 8) in The American Journal of Psychiatry.
The researchers studied callous-unemotional (CU) behaviors, such as lack of empathy and emotion, and found that toddlers with these behaviors have the worst behavior problems years later.
"These are signs for parents and doctors to watch out for, as they may signal more than just the terrible twos," said Luke Hyde, assistant professor of psychology at the University of Michigan and lead author on the study.
"Children with CU behaviors lack empathy and guilt, and may go on to develop antisocial disorders and behavior problems such as fighting, lying and stealing as adults, and may even be at risk to develop psychopathy," reported Jenae Neiderhiser, professor of psychology at Penn State, who was part of the research team and co-led the collection of data informing this study. "CU behaviors are very distinct from other behavior problems. If we can identify these kids early we may have a better chance of intervening in a child's development."
Beyond identifying these behaviors as early signs of trouble, the researchers' newest work sheds light on the origins of CU behaviors. Decades of research have shown that harsh and negative parenting is linked to the development of antisocial behavior.
Work by Hyde and University of Michigan research fellow Rebecca Waller has shown that this type of parenting is also linked to the development of CU behavior. "The challenge in this research has been knowing the true origins of these behaviors, because parents both parent their child and provide their child's genes. So it's been difficult to know if we're seeing that parenting causes CU behaviors, or just a sign of the genes being passed to the child," noted Hyde.
"To our knowledge, this is the first study to focus on the causes of early CU behaviors. It's important, because once we know the causes of CU behaviors, prevention programs can be developed to target younger children, whose behavior may be more easily modified," Neiderhiser explained.
To examine the role of nature versus nurture, the team followed 561 families in the Early Growth and Development Study, an adoption study which documented biological mothers' history of severe antisocial behavior, as well as adoptive parent and child behaviors. Observations of adoptive mother positive reinforcement took place when the child was 18 months of age. At 27 months, researchers examined the child's behavior.
The team found that antisocial behavior in the biological mother predicted CU behaviors in their children who were adopted into homes as infants. This was despite the biological mothers having limited or no contact with the children, indicating that CU behaviors were inherited. However, the team also found that high levels of positive reinforcement by adoptive mothers helped to mitigate CU behaviors in their adopted children.
"While we observed early CU behaviors being passed down from biological parents, our results showed compelling evidence that parenting is an important factor in the further development of CU behaviors as the child grows," said Waller.
"These findings are important because they mean that treatment programs that help parents learn to be more positive can help stem the development of CU behaviors. Biology is not destiny and parents can play a major role in shaping their child's behavior, even if the child shows early warning signs of serious behavior problems."
The team will be following this group of children through early adolescence to determine if these behaviors persist beyond toddlerhood. "It's a very large study rich with data, so it will be interesting to see how it plays out as the children age," Neiderhiser said.