A healthy, well-adjusted individual (which I mean in the psychological sense) notices that GTA and video games in general are very nearly morally null. At best you can create a rather strained line between "desensitization" and the possibility that you will do something bad in the future, which I call strained not so much because it's impossible but just because someone trying to condemn bad behavior in GTA would really like a more solid argument than that, not based in so many assumptions and second-order effects. And if it's that bad you'd like to be able to show a clear line between the rise in play and a rise in violent crime when, if anything, the opposite has occurred. (Which is probably not causal based on this issue. But still, the opposite has occurred, which makes the argument about how bad GTA is even more strained and difficult to make.)

I play GTA and such as videogames, not as morality simulators, because as morality simulators they fail, because there is hardly any moral theory that applies to them. Utilitarianism doesn't tell me to be moral in GTA, because the utiles in my accidentally running down a pedestrian simply because I got impatient at a red light and just drove anyhow is null. Deontological ethics doesn't tell me to take good care of numbers in a computer, unless you adopt a set of rules that says otherwise purely in the name of being contrary for this post alone. (In which case I'd also like you to analyze the ethics of the numbers you changed simply in the act of posting your contrary reply.) Consequentialism doesn't tell me to be concerned about the value of numbers in a computer; I would have higher regard for the health and well being of an individual bacterium than a pedestrian in GTA.

If you tried to read my personality by how I play GTA, you're going to get a very wrong reading, because I am well aware of how null the whole thing is, and I act accordingly. Nor do I find myself learning very much about myself. Nor do I find myself meditating on how flimsy the moral structure is constraining me, because GTA is not "just like the real world except for a few minor differences". It is utterly unlike the real world. It is completely unsuitable for any sort of moral analysis because in a very real way, the entire idea of morality applying to GTA is simply ludicrous, as ludicrous as the idea that I am a psychopath from a family of psychopaths because when we play chess with each other we kill, kill, kill without mercy or concern for how the poor chessmen feel.