Exposure to violent video games was related to aggression for the participants of a study and their friends. Greitemeyer explains and undergoes a review of academic literature that has been done on the relationship between violent video games and those who play it. After looking at the various literature on the subject, Greitemeyer concludes that it is entirely possible that playing violent video games can be contagious in the sense that individuals are more likely to play violent video games if their social network also consists of violent video game players.
Greitemeyer conducted a study that involves giving a questionnaire to 998 individuals, which includes individuals and members of their social network.
Greitemeyer's study found that the participant’s and friends’ exposure to violent video games and their level of reported aggression were positively related, meaning that as exposure to violent video games increases, the level of reported aggression increases as well.
Greitemeyer, Tobias. 2018. "The Spreading Impact of Playing Violent Video Games on Aggression." Computers in Human Behavior, no.80: 216-219. November 17, 2017.
https://doi.org/10.1016/j.chb.2017.11.022