Behavioral genetics enters the courtroom

| June 9, 2014
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U.S. Supreme Court (Credit: David/Flickr)
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In the criminal court system, a defendant’s mental health and history of abuse are often taken into account when considering a sentence. But slowly, a defendant’s genetic information is also starting to enter the courtroom, often without the proper explanation and instruction about how to use the information.

We all have millions of mutations throughout our DNA. Some affect function, and some don’t matter at all, they are just a swapped out allele. A typical genetic screening would pick up these mutations, whether they’re harmful or not. But, a jury could be told a certain defendant has a mutation in a gene that predisposes him to poor impulse control, without being told his mutation is harmless.

There are already some cases of genetic defense in court, as Virginia Hughes describes at National Geographic:

Specific genetic tests are beginning to seep into court, too. In 2007, several psychiatrists and geneticists described their experiences presenting evidence at criminal trials related to two gene variants: a variant of monoamine oxidase A, which when mixed with child maltreatment increases the risk of violent behavior, and a variant of the serotonin transporter gene, which when mixed with multiple stressful life events ups the risk of serious depression and suicide. A couple of cases used these scientific links to argue that defendants didn’t have the mental ability to plan their crime in advance. But most of the time genetic evidence was used to mitigate sentences. In 2011, for example, an Italian court reduced a female defendant’s sentence from life in prison to 20 years based on genetic evidence and brain scans that supposedly proved “partial mental illness.”

So far, this information has mainly been used to reduce sentences, much like someone with a mental health condition or a history of abuse may have their sentences reduced. But, it might not be long before someone’s genetic factors for criminal risk come into play.

Take the case of UC Irving neuroscientist, James Fallon who found during the course of his extensive research on psychopathy that he carried many risk factors for the condition. In fact, he scored quite highly for the condition on genetic tests, brain imaging tests and behavioral inventories.

Why then, Fallon asks, was he spared a life of criminal behavior while the murders he studied were not?

One most likely reason is that although I have the genetic makeup of a “born” psychopath, some of those very same “risk” genes in someone showered with love (versus abuse or abandonment), from childbirth through the critical first few years of life, appear to offset the psychopathy-inducing effects of the other “risk” genes.

As genetics moves into our criminal justice system with the aim of predicting or explaining human behavior, it’s important to remember that genes are not destiny. As Fallon explains, there is a whole host of environmental factors that help determine who we will become.

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