12/20/2012 10:35 pm ET Updated Feb 19, 2013

Genetics Will Not Explain Newtown

The tragedy in Connecticut last week shook all of us to our core, angering us, and pushing us all to find fault somewhere to explain the devastation. As a country, we have pointed fingers at guns, legislatures, school security and mental health care -- anything that could help us make sense of this horrid devastation of our most valuable and vulnerable children.

Dr. H. Wayne Carver II, the Connecticut medical examiner in search of a cause, has turned to "genetic clues" to explain Adam Lanza's motives. Individuals with an autism spectrum disorder are not known routinely to exhibit violent behavior, so he reasoned that other genetic markers may explain his psychopathic behavior. At this time, however, no such genetic clues exist that could be used to explain his actions.

Genetics and environment interactions that produce a disease like diabetes are extremely complex. The factors that lead to an individual's behavior are even more complicated.

It is not clear that an identifiable disease exists that could or should be associated with Lanza's extreme and rare behavior. If such a disease does exist, there is almost certainly no variation in a gene or genes that medical examiners could detect that would be diagnostic for the disease.

While there may be a genetic component that contributed in some small way to Lanza's psychosis, the notion that genetics somehow may explain the killings is erroneous. Genetics do not determine behavior. Genetics may predispose a person to behave in a certain way, but do not dictate how a person acts on his emotions.

Genetic markers have been associated with violence, such as the so-called "warrior gene" denoting the marker in the gene MAOA associated with a propensity to react aggressively to a stimulus. This marker also has been associated variably with individuals more likely to have high debt, low credit ratios or be high-functioning CEOs.

But using MAOA or variations in any other gene to attempt to diagnose a person with a predisposition to violence or predicting a person's likelihood to become violent is impossible and irresponsible at this time. The results of Lanza's MAOA genotype would only be useful in a research study of similar psychopaths that also considered environmental stimuli in the personal lives of violent individuals. We encourage such research to understand how mental health symptoms are predicted by genetics, but discourage the use of genetics to predict behavior.

More than anything, we would like to be able to predict and prevent such devastation in the future. Understanding "genetic clues" in the Lanza case, if any exist, would require considerable, careful research and analysis in context of the case and in comparison to other cases. But Lanza's genetic markers will not explain why he did what he did nor prevent future occurrences.

Sara Huston Katsanis is a genetic policy researcher at Duke University. David Kaufman is director of research at the Genetics and Public Policy Center at the Berman Institute of Bioethics at Johns Hopkins University.