Shared Environment ©

The search to explain criminal behavior is an ongoing focus in psychological studies. Identifying contributing factors of criminal behavior help to determine how and why a tendency to act criminally may occur in some individuals. The issue of nature vs. nurture has been a prominent issue in psychology and the attempt to uncover the causation of criminal behavior. While nature describes heredity as being an influence to behavior, nurture describes the environment as having a prominent role in psychological behavior (Guirguis, 2004).

One method of probing the issue of nature vs. nurture is by studying the phenomenon of criminal behavior through twin studies, in which researchers discern between genetic and environmental factors (Bartol & Bartol, 2008). A shared environment is an environment shared by the twins in which experiences and upbringing are similar (Bartol & Bartol, 2008). This is an important aspect of genetic research on crime because it incorporates the environment with what may be considered predetermining factors. Therefore, the environment cannot be entirely ruled out of observed behavior. A shared environment can also help distinguish what factors of behavior are more influential by environment and which are more genetically driven. One particular twin study revealed that non-aggressive behavior was significantly affected by the shared environment of the participants, whereas aggressive behavior seemed to be influenced more by genetics (Ishikawa & Raine, 2002).

A shared environment will most likely be responsible for resemblances between family members, whereas a nonshared environment may be comprised of factors that help explain differences between family members (Newell, 1999). Many studies have shown that the influence of a shared environment had more significance on behavior before the age of fifteen while genetic factors showed more relevance after the age of fifteen (Newell, 1999). According to Newell, “research on juvenile delinquency by McGuffin and Gottesman (1985), yielded concordance rated of 87 percent for identical twins and 72 percent for fraternal twins, suggesting only a modest genetic component while implicating a large influence of shared environment for these age groups” (Newell, 2008, p. 23). The persuasive findings of this study show the implications of a child’s upbringing and home environment and how these facets of childhood have a strong impact on behavior. It may also show that genetically influenced behavior has more potential of being modified than the deep-rooted environmental imprint on an individual. This would support the importance of a shared environment in terms of genetic research on crime.

References

Bartol, C., & Bartol, A. (2008). Criminal behavior: a psychological approach (eighth edition). Upper Saddle River, NJ: Pearson/ Prentice Hall.

Guirguis, S. (2004). Nature vs. nurture. Retrieved from http://www.nuc.berkeley.edu/courses/classes/NE-
24%20Olander/Equalitarinism_vs_Hereditarinism.htm.

Ishikawa, S., & Raine, A. (2002). Behavioral genetics and crime. Retrieved from http://www- bcf.usc.edu/~raine/Behavioral.Genetics.Crime.pdf.

Newell, C. (1999). Genetic influence on impulse and aggression related crime: a historical
review of
related research data and field research project. Retrieved from http://opensiuc.lib.siu.edu/cgi/viewcontent.cgi?article=1140&context=uhp_theses.