The researchers examined data from children who were nine months to five years old. The information was collected from the Early Childhood Longitudinal Study Birth Cohort. 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, Barnes said, found a link between genetic predisposition and environmental influences, in this case, spanking only in boys.
He said that "It did not affect females. Males who were spanked and had the highest genetic risks displayed the most aggressive behavior compared to other males."
Barnes said the researchers have been studying childhood levels of aggression to see how and why they are influenced by genetic risks. For example, acts of aggression included temper tantrums and disruptive behavior.
The 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.
Barnes further said that the study's findings could be an indicator of when interventions may be most beneficial.
He 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. The targeted intervention may be to reduce spanking across the board."