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.
For instance, Caitlin J. and Institute of Technology (2005), have shown that both criminal and anti-social behavior can be related to both genetic and environmental factor. In fact, they argue in order for anyone to clearly understand to what degree genes and environmental factors influence a person’s behavior especially those with criminal and antisocial behavior, other than reports submitted by both parents and teachers, more observational studies are necessary (Caitlin J. and Institute of Technology, 2005). However, many are those who disagree with such a proposition due to the fact that sometimes it can be very difficult to validate information collected from those sources.
For those who disagree with the idea that observational studies and parental sources are two credible sources to get information on whether or not criminal behavior is influenced by one or another and to what degree, they suggest the best way to gather that information is by conducting twin, family, and adoption studies (Caitlin J. and Institute of Technology, 2005). In fact, based on a study conducted on DZ and MZ twins, the result shows that there is little sign that can demonstrate the close relationship that exists between hereditary and criminal behavior. However, when comparing twins with antisocial behavior it is evident that hereditary plays an important role in the development of anti-social behavior as well as many other forms of aggressions and criminality.
The same result found for the study of adoption and family, there are some significances that link criminal or antisocial behavior to genes, however, such a significance is not strong enough to make a strong conclusion due to the fact that most of the studies done on that matter cannot be replicated. When comparing genetically related individuals with such behavior with nonrelative individuals living in the same environment, the results show that there’s greater accordance of anti-social or criminal behavior in related individuals than nonrelated ones. The truth is that children influence by both their parents’ genes as well as the environment in which they are being raised. For that reason, there is not enough evidence to show between the environment and genetic factors, which one influence criminal behavior the most. On top of all that, Laura B. et al. (2014) and Raine A. et al. (2003).
In a study conducted by observing individuals’ differences, their conclusion show that “various correlates of anti-social behavior, as well as certain personality aspects of a person, such as impulsivity, sensation-seeking, risk-taking, and callous-unemotional traits, are known to be influenced at least partly genetically (Laura B. et al., 2014 and Raine A. et al, 2003). They also show that psychiatric outcomes related to antisocial behavior and criminality, such as antisocial personality disorder, gambling problem, and the use and abuse of drugs and alcohol are also being influenced by certain genetic factors. However, they also argue that genetic factors have different types of influences on different types of crimes (Laura B. et al., 2014 and Raine A. et al, 2003).
Laura B. et al. also show that shared environmental effects among those with antisocial or criminal behavior who are being reported by their parents and teachers, and those who are being reported by themselves or based on governmental reports, the rate is much higher among those reported by both teachers and parents. Laura B. et al., argue that the reason for such a difference is because most of the studies conducted on children with antisocial or criminal traits are heavily rely on parents and teachers’ testimonies or observations more than scientific research.