Can Brain-Imaging Show Some People Are ‘Born Murderers’?

Brain imaging studies have shown a link between genetics and violent behavior, suggesting that some people are born murderers (with some very important caveats).

Sandy Hook shooter Adam Lanza’s brain was dissected and parts sent to the UConn geneticists for a DNA analysis, making him the first mass killer to have his genome looked at in-depth. Whatever the results are, the idea that violence can be inherited is highly controversial, and further study creates the potential for stigmatization and deep ethical dilemmas.

According to Popular Science, even the DNA analysis of Lanza’s brain is being shrouded with an air of mystery. Neither the geneticists or the medical examiner who sent the brain tissue would even say what the researchers were looking for, but there is enough background research to hazard a guess.

It’s been about two decades since geneticists linked a defect in the x-chromosome with violent behavior. Specifically, the one that codes the enzyme monoamine oxidase-A (MAOA), known in the media as the “warrior gene.”

According to the Guardian, Adrian Raine was one of the first to use brain-imaging to explain violent crime. His 1994 paper was so controversial that it was quickly labeled "racist and ideologically motivated." [Photo by Matthew Simmons/Getty Images]

Hints that there was a genetic link or “born murderers” came from looking at families of killers and violent criminals. In 1978, a woman walked into a hospital in Nijmegen, Netherlands, claiming that an alarming number of her male relatives were violent offenders. One tried to rape his sister, another tried to run over his boss with his car. The line of criminals that can be traced all the way back to the 1870s.

Doctors studied the woman’s family looking for genetic abnormalities, which ultimately led to the MAOA defect. The problem appears on the x-chromosome, which might partially explain why men are more prone to violent crime. Women have two x-chromosomes, so if one is defective, the other can step in.

Dr. Kent Kiehl studies the brains of murderers and other violent criminals, and he’s found how genetic problems could partially explain the criminal behavior. Using a $2.2 million functional magnetic-resonance-imaging scanner (fMRI), he created a database of about 4,000 criminal brains. He concentrates on psychopaths and psychopathic behavior.

Roughly one percent of all people are psychopaths – within the prison population, it’s 16 percent. People with this mental condition are hard to diagnose, but suffer from a detached emotional state, lacking empathy and sympathy for others. Criminal psychopaths, on average, commit four violent offenses before the age of 40.

Dr. Kiehl has become a leading expert on psychopathy and schizophrenia through his brain-imaging research, and he’s found a link between certain defects in the limbic and paralimbic cortex and psychopathic behavior. Those areas of the brain process/generate emotions, control impulses, and help in maintaining concentration. Psychopaths in his studies have less gray matter in those areas, as well as a smaller amygdala, a part of the brain connected to empathy and emotion.

Brain-imaging and genetic tests for violent criminals is an ethically difficult problem. Could is lead to young people being profiled by their genes? [Photo by Oli Scarff/Getty Images]

In short, Kiehl says these people just have “different brains,” and that 50 percent of the abnormalities are explained through genetics.

Nevertheless, the “born murderer” issue is a controversial one.

Behind the research lurks the scary prospect of people being branded murderers the moment their genome is studied, and forced to live under stigmatization and suspicion, even without committing a crime.

Daniel Weinberger, director of the Lieber Institute for Brain Development at Johns Hopkins University, explained that genes don’t automatically make a person a born murderer.

“If you inherit small glitches, little pieces of noise, this sets you on a path. But it doesn’t determine you will end up with mental illness. These glitches aren’t fate. They are for risk. Environmental factors are at play too.”

Neuroscientist James Fallon has a more personal connection to the research according to NPR.

Fallon’s family has a history of violence stretching back to 1667, and his brain looks similar to that of a criminal psychopath. But, he’s in no way a violent criminal, which he thanks in part to a great childhood with loving parents.

Scientific research into the idea of “born murderers” is new, and despite years of brain-imaging tests and DNA analysis, it’s far too early to put the studies into much practical use, which leaves ethicists some time to mull the possible consequences.

[Photo Illustration by Ian Waldie/Getty Images]