Genetic and environmental factors in criminal behavior

Nature vs. Nurture in Criminology

The nature/nurture issue has been a controversy in professional circles for many years. In criminology then, some hold that criminal behavior is socially (nurture) influenced, while others are of the opinion that genetics (nature) play a substantial role. While it is true that the environment in which a person is raised plays an important role in possible criminal tendencies, studies show that the innate nature of a person plays a very prominent role in criminal behavior. In fact, Plomin (1990, p. 108) states that genetic influence on body build and neurologica may affect such areas as mental ability, personality and psychopathology, thus also influencing personality traits that would include criminal tendencies.

Adopted Children and Twins

In order to determine the extent of genetic influence on behavior, as well as psychological disorders, studies have been conducted involving adopted children and twins (Plomin, 1990, p. 109). Prominent studies done on adoptees in Denmark for example suggest that nature does indeed play a significant role, regardless of the circumstances in the adoptive families. Where neither adoptive nor biological parents were criminal, 14% of a group of 2,492 adopted sons had at least one criminal conviction. Where the adoptive parents, but not biological parents of a group of 204 adopted sons are criminal, 15% of these sons have at least one criminal conviction. The most significant finding is the 1226 cases investigated where the biological parents, but not adoptive parents are criminal. Of these sons, 20% has a criminal record, and where both adoptive and biological parents are criminal, 25% has a criminal record.

Harris (1999) cites the case of Amy and Beth, two identical twins, each adopted by a different set of parents. Despite the contrasts between their environments, both Amy and Beth suffer from the same personality problems. Eaves, Eysenck and Martin (1989, p. 20) mention that the prominent similarity of twins is due to their genetic closeness, as well as the fact that they have the same parents. Obviously then it follows that similar personality disorders such as those experienced by Amy and Beth, despite contrasting environments, are due to their genes, which are similar. This substantiates the hypothesis that nature is a prominent component of behavior and behavioral disorders, and would then also be true of criminal behavior.

Harris (1999) makes a case for nurture through citing behavioral genetic studies of twins or siblings. The environment shared by these individuals often affect both in strengthening their genetic propensity towards crime. Twins or siblings growing up in the same home are likely to display the same amount of criminality:

both are or are not criminal. The home environment itself may however not have an influence, but it is true that socialization occurs both inside and away from home. The siblings or twins for example share the same peer group, which can influence them or strengthen their genetic criminal nature. It is significant that the correlation in criminal nature for these twins is higher when they are raised together than when they are raised apart.

Twin studies are however inconclusive, and it is difficult to determine the exact amount of nature and nurture that play a role in criminal tendencies. (Gale Encyclopedia of Psychology, 2001.) While there are definite similarities that correlate more closely than those between fraternal twins, identical twins have also shown differences, even when raised in the same environment. Here it is possible that small differences in genetic make-up dictate that each twin reacts differently to environmental factors, and thus develop differently, although with the same basic genetic make-up.

It is however also true that many twins separated at birth develop startling similarities, which is then ascribed to genetics. Differences in these cases are ascribed to the environment in which each grows up.

Studies of twins in different environments are inconclusive, since the differences are often arbitrary, and not scientifically measured. Thus the environment could have a greater impact than supposed by some studies, where results indicate genetic similarity despite a difference in environment. Thus it is impossible to exactly determine the amount of nature and nurture involved in personality development. It is however possible to determine the various factors responsible for criminal tendencies, which encompass both genetic and environmental elements.

The Role of Nature

Harris (1999) focuses her study on the validity of heredity in behavior and personality. Nature, as mentioned above, is the foundation of the personality, which is then further shaped by the environment, or nurture. Thus criminal tendencies may be in-born, but an environment free from criminal parents or friends can influence such a person for the better.

Harris also gives heredity the responsibility for problem children born to problem parents. The author cites various personality problems that could also result in criminal behavior. These include a tendency to be active, impulsive, aggressive, and quick to anger. This often leads to the related problem of being bored quickly, not being afraid to get hurt, and emotional insensitivity. This is exacerbated by a muscular build and a slightly lower than average IQ. All of the above are genetically regulated traits, which sparks a certain reaction to external stimuli.

It is clear that the role of nature in criminal tendencies, as in all other parts of human nature, cannot be denied. It forms the basis of traits to be developed throughout life. Thus, although the environment plays a vitally important role, I believe that a genetic disposition towards crime is a prerequisite for regular criminal activity. Conversely, if this genetic disposition is regulated by a positive social and home environment, it is my belief that criminal tendencies can be suppressed by a more positive lifestyle.

Conclusion

The only conclusive paradigm created by the nature/nurture controversy is the fact that more study is required to enlighten the issue. The singular paradigms of nature vs. nurture have however changed to include both for their role in the psyche of the criminal. Primarily I believe nature is responsible for creating a criminal mind, with secondary influences from the environment, either at home or through socialization. It is hardly conclusive that all persons with in-born criminality would succumb to the urge to commit crime.

The fact that nature and nurture work together to create the criminal can be used to combat this process. It is mentioned above that parents with problems often have children with problems. A parent with criminal tendencies, who has been rehabilitated, can then help a child with the same tendencies to cope with problems experienced as a result.

A deeper understanding of the genetic nature of criminal tendencies can also help in the rehabilitation of criminals. Certain activities can be created to help these people channel criminal thoughts and activities into other, more wholesome activities. Again, the children involved should be considered. Children of criminals can then take part in programs to provide an environment where crime is not seen as a socially laudable activity.

Genetic studies have been of great help in many areas of life. This has been true in the area of child-rearing. An understanding that children are not "blank slates" has helped parents to adjust their parenting styles to the particular personalities displayed by their children. Such studies can then also be conducted in prisons. Obviously the issue has enjoyed some academic attention. However, no rehabilitative efforts have been made. In order to provide a more wholesome nurture, the nature inherent in every human being, including criminals, should be acknowledged. In this way society at large can only improve.