It has been considered for a really long time that children repeat what they see in real life as a means to learn and assimilate information while growing up. This is something that many scientists and child psychologists hold for true.
That, however, doesn’t mean that children would actually resort to very violent behaviour, if presented to them. Take, for example, miniclip games that are considered violent or agressive. Although the graphic images can be very expressive, miniclips usually have a story line that explain the reasons behind it and how the bad guys deserve to be punished and the good guys to win.