There is a large number of twin, adoption, and family studies that have been conducted for the past decades, using a classical approach. Interestingly, they all have provided abundant information about how impactful both genes and environment are on a person’s behavior, especially those with antisocial and criminal behavior. However, those studies are varied in their definition of criminal and antisocial behavior as well as how they are being measured. But, despite the different types of approaches, results show that they all agree that both genetics and environment play a very important role in antisocial and criminal behavior’s outcomes
