Genes & Violence - Ahan

How can one know what is going to happen before it does? Do we humans possess markers for future behavior? Can genes and other traits serve as literal “tea leaves,” and once successfully decoded, help to predict our actions? These are all questions that scientists around the world are trying to answer - to what extent is our future pre-determined, or are is it all free will. There have been recent discoveries that have linked previous experiences, hormones, and genes with future actions.

One of the leading researchers in this field is Stanford biologist, Robert Sapolsky. In his 2017 TED talk, Sapolsky articulated his idea that the cause of some of our behaviors can be traced back not only minutes but millions of years before. The core of the brain’s decision-making engine is called the amygdala. The amygdala helps to determine our response to fear and can be affected by factors such as stress hormones and environment. Most of us already know that if we are stressed out, we are more likely to be “on edge” and irritable. However, we can try to predict this even before birth with genetics. Monoamine oxidase A (MAO-A) is an enzyme that is present in humans and is encoded by the MAOA gene. This gene has become known in the popular media as the “warrior gene” because its deficiency has potential links to antisocial behavior and violent crime. A European study in 2015 showed that a deficient MAOA genotype is associated with extremely violent behavior and even attributed 5-10% of severe violent crime in Finland to this gene (Tiihonen et al. 786).

Now, the evidence in the case of MAOA is becoming more clear-cut, there have now been multiple studies showing a correlation between this gene and violent behavior, but does this classify as a prediction of behavior? This is a critical question, as our society is including more scientific fact in our decision-making. In 2006, this gene was successfully used in a Tennessee courtroom to prevent a death penalty conviction. In the case of Bradley Waldroup, a jury convicted him of manslaughter over premeditated murder after being shown evidence that he had a deficiency of the MAOA gene (Hagerty). 

It is important to begin to ask ourselves whether these factors are accurate predictors or if they just influence our free will and how much we should rely on these factors, especially in a court of law. While genes like MAOA, and undoubtedly others, are probable indicators future intentions, we must be cautious about how they are used and explained. In the Waldroup case, it is doubtful that another jury will reach the same conclusion as the first based on the same scientific evidence. The unfortunate truth is that we just do not have enough information to make an accurate predictive model. The optimal predictive model for these cases will take sustained data collection and analysis over generations of a large population.

While discussing the prediction of violent crime, we should briefly touch on some new technology that is starting to appear in courtrooms across the country. COMPAS, short for Correctional Offender Management Profiling for Alternative Sanctions, is a new tool developed by a private company. The point of this tool is to determine a risk of recidivism based on a series of questions. However, a 2016 analysis of COMPAS by ProPublica showed that race played an overwhelming factor in COMPAS’ prediction, even while controlling other variables. Certain groups were given higher scores just based on race even though, in reality, they were at greater risk of recidivism. Now, this software does not take into consideration the MAOA gene or any other biological factors, but even if it did, how accurate would such a prediction be.

This piece might raise more questions than answers - I know it did so for me. There are so many advances being made in genetics that can open the door for future prediction, but they must all be taken with a grain of salt until they are proven to work. Any accurate predictive model requires much tuning, and in the case of humans, this can take several generations and hundreds of years.

Works Cited

The Biology of our Best and Worst Selves. Anonymous Perf. Sapolsky, Robert. TED, .

Hagerty, Barbara. "Can Your Genes make You Murder?" 7/1/ 2010. Web. Sep 19, 2017 <>.

Larson, Jeff, et al. "How we Analyzed the COMPAS Recidivism Algorithm." ProPublica -05-23 2016Web. Sep 19, 2017 <

Hardwired. NPR, 2017. Podcast.

Tiihonen, J., et al. "Genetic Background of Extreme Violent Behavior." Molecular psychiatry 20.6 (2015): 786. MEDLINE. Web.