In order to do further research into the genetic predispositions of psychopathy many other various researches have been conducted into wide spectrum of individuals and families. They studied people with no other genetic history of psychopathy in their families, twins, parents, family relations and much more. Due to those researches and studies we deepen our knowledge regarding psychopathy and if it comes to the time where we will find the environmental or genetic factors or both we might even know how to prevent people from becoming ones and know what treatments to be used.A research to find the genetic and environmental influences on psychopathic personality traits was conducted by H Larsson et al. they have created a sample of just over 1,000 monozygotic and dizygotic pairs of twins which were between the age range of 16-17. in a sample of 1,090 monozygotic and dizygotic twin pairs, aged 16-17 years. The findings of this study have presented us with a strong genetic influence on psychopathic traits. Results showed a strong genetic influence behind the higher order “psychopathic personality” factor which is underpinned by the three psychopathic personality dimensions. Furthermore, other important genetic influences were also found in the callous-unemotional and in the impulsive/irresponsible dimension however, not in the grandiose/manipulative dimension (21)Additionally, another study into genetic contributions in twins was summarized by various researchers such as: Christiansen (1974) and Hutchings (1972). Out of all of the twins and adoption studies only two have strongly supported the hypothesis that the genetics factors are important [Bohman (1972 and Zur Neiden (1951) studies]. Bohman was unsuccessful in finding any sort of association between criminality in biological fathers and criminal behaviour in 10/11 year old adoptees. However, to counterargument this statement West et al., stated in his data sample that the criminality in parents is more strongly associated in felony in offsprings after the puberty than before puberty. This is not fully confirmed thus needs further study into this but it already brings Bohman’s conclusion into questioning as the children used in his study were through minimal risk period for antisocial behaviour which leads to his observations being inconclusive. Furthermore, another research by E. Vinding et al., (2005) searched for any kind of evidence for substantial genetic risks for psychopathy in 7 year olds. It was deduced that the young individuals that have early warning signs of psychopathy characteristics such as callous-unemotional (CU) traits and high levels of antisocial behaviour (AB) could be reported in childhood. Teachers, at the end of the school year, have provided the researchers with the gradings to both callous-unemotional and antisocial behaviours coming from twin pairs. In order to do various analysis of twins they have selected same-sex twins pairs where one twin has scored at least 1.3 on the CU scale and the same process for the AB scale. Individuals who had the extreme AB as well as extreme CU were put into another group. The analysis of twins has shown us the high levels of CU is due to strong genetic influence. (28)Additionally, Larsson et al., decided to examine the genetics factors in order to explain the link between psychopathic personality (PP) and antisocial behaviour (AB). It’s known that both PP and Ab are influenced by genetic and environmental factors but it is not know much about which of those factors contributes to which trait which is PP and AB. They decided to do a longitudinal study is an observational method where the data is gathered on the same individuals/objects over a long period of time. They chose a population-based twin sample which consisted of nearly 1500 twin pairs which were born in Sweden between May 1985-December 1986. At two intervals: in 1999 (age 13) and 2002 (age 16) the twins received the mailed questionnaire which consisted of questions about their personality and everyday life. It was found that a common genetic factor was rigged towards both PP and AB whereas a familiar shared environment only influenced AB. This implies that the genetic overlap between psychopathic personality and AB may bring our attention to genetic vulnerability in externalizing psychopathology.