Superheroes in Hollywood blockbusters conduct more violent acts on screen than the villains they are battling, says a study being presented at this year’s American Academy of Pediatrics conference.

The study looked at the top-grossing superhero films of 2015 and 2016 as ranked and categorized by Box Office Mojo, a site tracking box-office receipts. According to that site’s database, some of the most popular superhero films in those two years were Captain America: Civil War, Batman v. Superman, Suicide Squad, Avengers: Age of Ultron, Deadpool, and Ant Man.

On average, the films showed an average of 23 acts of violence per hour by the films’ protagonists, compared with 18 violent acts by antagonists. Male characters had 34 violent acts per hour, nearly seven times as many as female characters.

“Children and adolescents see the superheroes as ‘good guys,’ and may be influenced by their portrayal of risk-taking behaviors and acts of violence,” said the study’s lead author, Robert Olympia, a professor of pediatric medicine at Penn State College. “Pediatric health care providers should educate families about the violence depicted in this genre of film and the potential dangers that may occur when children attempt to emulate these perceived heroes.”

According to the abstract of the study, the most common violent act of superheroes was fighting, with 1,021 instances, followed by destruction of property, murder, bullying, intimidation and torture. For villains, use of a lethal weapon was most common, with 604 instances counted.

The researchers who conducted the study pointed to previous studies that have shown an increase in aggressive behavior in children when parents signal approval of violence by passively watching superhero films with them. Instead, they urged parents to take a more active role by discussing the violence they see in the films with their children.