Aggression
Some scholars believe that behaviors like aggression may be partially learned by watching and imitating people's behavior, while other researchers have concluded that the media may have some small effects on aggression. There is also research questioning this view. For instance, a long-term outcome study of youth found no long-term relationship between playing violent video games and youth violence or bullying. One study suggested there is a smaller effect of violent video games on aggression than has been found with television violence on aggression. This effect is positively associated with type of game violence and negatively associated to time spent playing the games. The author concluded that insufficient evidence exists to link video game violence with aggression. However, another study suggested links to aggressive behavior.
Reciprocal determinism
Researchers believe there is a genetic link to impulsive aggression through the impact of a gene on the production of an enzyme called Monoamine oxidase A (MAOA). The MAOA gene reduces the production of MAOA, leading to increased incidents of impulsive aggression. A 26-year study in New Zealand found strong correlation between experience of childhood abuse and criminal or violent behavior in males with the MAOA gene. In that study, impulsive aggression was found to be nine times more likely to manifest in males with the gene who were abused than in abused males without the gene or males with the gene who had not been abused.