Tammy Wilgenbusch, a clinical psychologist with University of Iowa Children's Hospital, said that at this age, children are developing their personalities and independence so they may be more likely to take their insecurities out on or try to wield power over others.

"By later adolescence, they have a better sense of self and are less likely to take insecurities out on others," Wilgenbusch said in a statement.

Bullying is a negative or aggressive act that is systematic and ongoing that can be instigated by one person or a group of individuals, Wilgenbusch explained.

"Typically, the person doing the bullying is seen as more powerful, whether it is physical or social status or better language skills," Wilgenbusch said.

However, studies show that children who display more anger are more likely to bully because they do not have proper anger-management skills, Wilgenbusch explained.

If parents learn their child is bullying, they should talk to their child.

"You can't just tell them to stop," she said. "You need to really talk with them to help them learn to empathize with the other person and to think about why they're bullying and what they are getting out of it."