Theories have been used in many subjects such as science, philosophy, criminology etc… They are what we use to help us gain an understanding of the world we live in. In criminology, it is used to help us define crime; what causes crime and why an individual chooses to commit a crime. These models of understanding come from three main explanations: sociological, biological and psychological. However, the two best known are biological and psychological. The biological focuses on the relationship between how criminal traits can be greatly influenced by environment and heredities. Rather than focusing on genetic traits, the psychological approach focuses on the individual's criminal behavior and is broken down into several components. Early positivist criminologists are known for their theory of “born criminals” as they were greatly inspired by Darwin and his theory of evolution. The biological approach holds that genetics plays a vital role in influencing behavior. In fact, this thought is also related to the famous Nature vs. Nurture debate, which later led to the understanding that it should be Nature vs. Nurture (Anderson, 2014). Biological Reasoning conducted twin studies to test the genetic traits of two types of twins (dizygotic and monozygotic twins) using concordance rates. As a result of these experiments, it is recognized that monozygotic twins tend to have higher concordance rates for criminal behavior than dizygotic twins. Therefore, it reveals that there is a strong genetic basis for criminal behavior (Anderson, 2014). Not only did genetics play a role between the twins, but the environment the two lived in also had an effect in bringing out those criminal traits. This has been tested through adoption studies, which have been useful for “separating genetic and environmental influences” (Anderson, 2014, p.149). Adoptees with criminal biological parents were tested and observed while growing up in a household of noncriminal adoptive parents. Consequently, it is believed that if the adoptee is raised in an ethical environment, without biology, it is difficult for the psychological approach to support its theories. Like key biological factor variables, this aids the psychological approach in assessing risk factors. For example, Farrington's long-term antisocial potential, which includes key factors of impulsivity, low IQ etc., usually requires biological aspects (Heidt, 2014). Impulsivity may be the result of an imbalance of hormones or neurotransmitters, while mental weakness may be due to genetics. Similarly, a poor diet that causes low amino acid levels and brain damage to the frontal lobe also leads to long-term antisocial behavior. People in this category are prone to violent behavior which helps the criminologist assess risk