Nature vs. Nurture in the Criminal Justice System


The pace of research into genetic factors that may influence how we think and act has increased drastically in the last few years. Some forms of mental illness have a strong hereditary component. For example, scientists are trying to determine how genetic factors make some people more susceptible to disorders like schizophrenia, depression and alcoholism. They also are exploring the contributions of genes to certain personality traits, like shyness and impulsiveness.

Scientists currently believe that the vast majority of human behaviors and traits reflect a complex mix of genetics and the environment. It is unlikely that they will discover single genetic mutations that determine such characteristics as intelligence or that fully account for why some people become aggressive or violent.


It is 2010, and Joe Schmoe has been charged with assault. The physical evidence supporting his guilt is overwhelming and he pleads guilty. In preparation for his sentencing hearing, Joe's lawyer asks him to undergo a series of genetic tests to determine whether he carries any of four genetic mutations that have been associated in research literature with violent behavior. The tests, while controversial, show that Joe's DNA does, in fact, contain all four mutations. Based on these results, Joe's lawyer will argue that Joe should be sent to a psychiatric facility rather than to state prison. He claims that because Joe's genetic status predisposed him to this violent act, it would be unfair to sentence him as a criminal for behavior over which he had essentially no control.

Discussion Questions:

  1. If you were the judge at Joe's sentencing hearing, how, if at all, would the results of this controversial genetic test influence your decision?

  2. How would your decision be influenced if Joe had only 1 of the 4 mutations associated with violent behavior?

  3. What would be your decision if Joe was shown to suffer from a mental illness such as schizophrenia? How come?

  4. If Joe gets sent to prison and tries to get released on parole fifteen years later, should the fact that he may have a genetic predisposition to violent behavior be used to keep him in prison, even if his behavior has been consistently good during his incarceration?

  5. In the future, should all newborn babies be screened to determine if they have genetic mutations that could be linked to violent behavior? How come?

  6. What if a medication became available to treat people with these mutations?

Last updated: March 30, 2012