(WXYZ) - Less parental warmth and a more harsh work environment affect how aggressive children become and whether they lack empathy and a moral compass, according to a new study.

Researchers at the University of Michigan, University of Pennsylvania and Michigan State University studied 227 pairs of identical twins. They analyzed differences in the parenting that each twin experienced to determine whether the differences predicted the emergence of antisocial behaviors.

The study found that the twin who experienced harsher treatment and less emotional warmth had a greater chance of showing aggression and a lack of empathy and moral compass.

These characteristics are known as callous-unemotional traits.

"The study convincingly shows that parenting—and not just genes—contributes to the development of risky callous-unemotional traits," said Luke Hyde, U-M associate professor of psychology. "Because identical twins have the same DNA, we can be more sure that the differences in parenting the twins received affects the development of these traits."

Read the full article at WXYZ.