According to the findings of a new study, children who play violent video games regularly might end up having increased levels of violent thoughts and behavior. The report is based on data from Singapore and found that children who often play violent games even believe that hitting is acceptable and can have more aggressive tendencies than children who do not play violent games.

“Just like children’s bodies can be affected by what they eat, their brains can be affected by what they repeatedly do,” Iowa State University researcher Douglas A. Gentile, who worked on the study, told Reuters.

Whether or not there is a link between violent games and violent behavior has been a point of debate in gaming circles and even Washington for years now. This new study doesn’t conclude anything definitively and its findings aren’t without controversy and debate.

The study, conducted over the course of three years, included around 3,000 children ages 8 to 17. Every year, the researchers asked the kids how often they play video games, which games were their favorites, and how much violent content was featured in the games.

The researchers also asked the children how likely they would be to physically strike someone if provoked. Other questions put to the children included asking for their thoughts about violence in general, whether or not they thought hitting was acceptable in some situations, or if they ever had dreams about hurting others. Children in the study also reported how involved their parents were in limiting how much time they spent playing games.

The study, Mediators and Moderators of Long-Term Effects of Violent Video Games on Aggressive Behavior, found that children who played more violent video games often had more fantasies about violent and reported that real-world violent was sometimes acceptable.

The correlation was about the same for boys and girls, even for children with and without a history of aggression and parents who were involved or detached from their gaming habits.

Stetson University media research professor Christopher Ferguson challenged the study.

“This is not a very good study,” Ferguson told Reuters. “This data set has been criticized before.” Ferguson said the design of this study is similar to a report that the United States Supreme Court struck down in 2011 in its landmark decision about violent video games.

Ferguson said one problem with the study is that children might be unlikely to self-report their feelings. This could skew the data, he argued.

“The research we have now has been very inconsistent,” Ferguson said. “There may be a connection to relatively minor acts of aggression, the equivalent of kids sticking their tongues out at each other,” but there is no evidence of a link to bullying, fighting, or school shootings, he said.

You can read the full study here.