A study co-authored by UT Dallas criminologist Dr. J.C. Barnes shows that the risk of problem behavior during childhood -- particularly for boys -- is greatly increased if children have genetic predispositions for these behaviors and if they are spanked by their parents.

"We found that genetic factors affect which children display aggressive behavior, but we also found that genetic factors matter more when children were exposed to spanking as a disciplinary tactic," said Barnes, an assistant professor of criminology in the School of Economic, Political and Policy Sciences.

The study titled, "Physical Punishment and Childhood Aggression: The Role of Gender and Gene-Environment Interplay," was recently published in the journal Aggressive Behavior. The researchers examined data from children who were 9 months to 5 years old. The information was collected from the Early Childhood Longitudinal Study Birth Cohort.

Barnes said the researchers found a link between genetic predisposition and environmental influences -- in this case, spanking -- only in boys.

"It did not affect females," he said. "Males who were spanked and had the highest genetic risks displayed the most aggressive behavior compared to other males."

Acts of aggression included temper tantrums and disruptive behavior, for example. Barnes said the researchers have been studying childhood levels of aggression to see how and why they are influenced by genetic risks. Genetic risk was measured by utilizing what is known as the twin methodology, a study design that allows for the comparison of twin concordance as a way to identify heritable influences on a trait.

The study's findings could be an indicator of when interventions may be most beneficial, Barnes said.

"Since we're tracing back to early childhood, which is a formative time, that suggests interventions could be targeted to that early time point in the life course," he said. "The targeted intervention may be to reduce spanking across the board."

The study was co-authored by Dr. Courtney Franklin at Sam Houston State University and Dr. Kevin M. Beaver at Florida State University.