Justice and Rule
Legend
I'm not saying that it can't be true, but rather there's nothing that shows it to be true. No studies that I know of and not one single time in my rather extensive personal play experience.
What I have seen are people that are more disposed towards playing their already present inner feelings in the game. You can tell the difference between someone who is roleplaying something distasteful and someone who is getting off on it now that they have an outlet. I quickly stop playing with the latter.
I mean, this was me just doing a brief look up of things. I know there are other ones out there. Really, there's definitely a link between what media we consume and how we form our biases and attitudes. It's perhaps most obvious with news media, but what we consume changes our attitudes as much as we pursue things that agree with our biases.
Now, attitudes and such are different than behavior: video games won't get you to shoot up a school, for example. But they can desensitize, help you form opinions and reinforce attitudes. That's just the nature of media.