Steven Spielberg’s 2002 film Minority Report, set in 2054, focuses on the PreCrime division of a police department. The PreCrime Unit’s job is stopping crimes before they occur. That’s now just 37 years in the future, and it is possible that sci-fi thriller accurately portrays the future. The answer may lie in genetic testing. Society has long pondered whether nature or nurture has more influence over criminal behavior. There are valid arguments on both sides of the issues, but recent studies point increasingly to genetic impact. In the developed world, most violent crime is perpetrated by relatively few individuals, and these people may share certain genetic traits.

The Anatomy of Violence

University of Pennsylvania professor and criminology department chair Adrian Raine works in the field of neuro criminology, studying the brains of criminals. He is the author of The Anatomy of Violence: The Biological Roots of Crime. Raine states, “Science shows that 50 percent of the variance in crime is under genetic control.” He also points out that 50 percent depends on environmental factors, with maternal smoking, drinking, and poor nutrition during pregnancy substantially upping the odds of the offspring becoming a violent criminal. On the other hand, fish consumption may lead to less violence, because of the neurologically calming effects of omega 3 fatty acids.

Violent Crime Genes

In a Finnish study published in Molecular Biology, an analysis of 900 violent offenders found two specific genes related to violent crime. However, the researchers stressed that most people possessing these genes did not go on to commit violent crimes. The two genes involved are:

• Monoamine oxidase A (MAOA) – controls an enzyme crucial for controlling the levels of serotonin and dopamine neurotransmitters in the brain. Serotonin helps regulate impulse and mood, while dopamine targets the brain’s pleasure centers. Various opiates increase dopamine activity. Because it causes increases in aggressive behavior, MAOA has been dubbed the “warrior” gene. Other research links the MAOA gene solely to Caucasians, and it appears to manifest in criminal behavior if the person was brought up in an abusive environment. That indicates nurture plays a role in nature when it comes to this gene.
• Cadherin  13 (CDH13) – associated with Attention Deficit Hyperactivity Disorder (ADHD), substance abuse, bipolar disorder, schizophrenia, and autism.

The MAOA gene was first identified in a notoriously violent Dutch family in 1993. The Finnish study did not find a link between MAOA and child abuse in its examination of violent criminals, but it did find a correlation between the MAOA gene and alcohol or amphetamine use when the crimes were committed.

A control group of non-violent criminals did not have this genetic makeup. “No substantial signal was observed for either MAOA or CDH13 among non-violent offenders, indicating that findings were specific for violent offending,” according to the study. Not all of the violent criminals in the study had these two genes.

In the Courtroom

So far, the “gene plea” has made some inroads in American courtrooms. In Tennessee, Bradley Waldroup was accused of the murder of his wife’s friend and the attempted murder of his estranged wife in 2006. The crime was particularly bloody – Waldroup chopped off his wife’s finger with a machete and cut her extensively, and shot her friend eight times. He was found to have the MAOA gene and a history of child abuse. The judge allowed a forensic psychiatrist to testify about the genetic predisposition over the prosecutor’s objections. The prosecution brought in another psychiatrist to refute the other’s testimony. The bottom line: Waldroup was convicted of voluntary manslaughter and attempted second-degree murder. The jury took his genetic profile into consideration and did not convict him of first-degree murder and attempted murder.   

More Research Needed

Approximately 20 percent of the population has the MAOA and CDH13 genes. Obviously, one out of every five people is not a violent offender. It is possible that you, the reader, are carrying these genes. So why does a small percentage of people with these two genes go on to commit violent crimes? While there’s increasing evidence that genes do indeed play a role in criminal behavior, much more research is necessary for definitive conclusions. The Minority Report era hasn’t yet arrived, and it may never happen. There’s little doubt we will learn more about the influence of genetics on the criminal mind and how to address these issues. While genetics are a contributing factor, current science makes it clear that how children with this genetic predisposition are raised makes a huge difference in whether they will lead normal or criminal lives. Adrian Raine agrees – his own physical and psychological profile put him on the spectrum of possible criminality. Instead of becoming a prisoner, he ended up a professor.

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