Violent video games don't necessarily lead to violent behavior, according to a study released by Aggie researcher Christopher Ferguson. He shares his results with GamePolitics.com.
I conducted a meta-analysis of studies associating violent video game exposure with aggressive behaviors. A meta-analysis involves collecting existing studies in the literature, and obtaining an over all effect size (i.e. degree of relationship) for all of the studies examined. This allows us to get a sense, not just for individual research projects, but rather for the overall result from combined studies in a field.
Overall results of the study found that although violent video games appear to increase people's aggressive thoughts (which it would not be surprising that people are still thinking about what they were just playing), violent games do not appear to increase aggressive behavior.
Publication bias appeared to be a significant issue for studies of aggressive behavior. Thus it was concluded that there is little evidence from the current body of literature on violent video games that playing violent video games is either causally or correlationally associated with increases in aggressive behavior.