Turns out, violent crime may be genetic

Is violence outside our control?
Is violence outside our control?
Image: AP/Pat Sullivan
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Our actions are often considered to be a product of our attitude or environment. But our genes may have more to do with this than we think. A new study found that a certain genetic makeup may be more prone to very violent behavior.

The study, published in Molecular Psychiatry, analyzed the genomes of 895 Finnish criminals who were placed in categories from non-violent to extremely violent based on the nature of their crimes.

Variants of two genes, MAOA and CDH13, were found to be associated with violent crime. Violent criminals, the 78 of whom had committed a total of 1,154 violent crimes, were linked most strongly to the genes, while the non-violent criminals were not associated with them.

It’s the first large-scale study to look specifically at genetics and criminal violence. MAOA, dubbed “the warrior gene” a decade ago by Science, the academic journal of the American Association for the Advancement of Science, has already been linked to aggression. The second gene, CDH13, has been previously linked to impulse control.

As the body of research relating genetics to criminal behavior grows, legal issues loom. Research on CDH13 has been decried by criminologists as abetting racist eugenic theories. Should genetic makeup play into a court’s consideration of a defendant’s responsibility for their actions? Genetics have appeared in defense lawyers’ arguments, and on at least one occasion have led to a lighter sentence.

Jari Tiihonen, the lead author of the study, said he believes that genetics shouldn’t be considered in court.

“There are many things which can contribute to a person’s mental capacity,” he told the BBC. “The only thing that matters is the mental capacity of the individual to understand the consequences of what he or she is doing and whether or not the individual can control his or her own behavior.”

He also stressed that because committing a severe, violent crime is extremely rare among the general public, the absolute risk associated with his findings is very low.