This sounds like a good plot for a spooky Twilight Zone episode – or an argument for scepticism about neuroscience determinism. A neuroscientist studying psychopaths and sociopaths finds that they tend to have low activity in the orbital cortex of the brain. It can’t do its job of inhibiting the amygdala, the part of the brain which regulates that id-type behaviors like rage, violence, eating, sex, and drinking. Like his own brain scan…

Then he learns that his family line contains at least eight murderers, including the famous Lizzie Borden (who took an axe and gave her father 40 whacks).

Then he examines family members for the MAO-A gene (monoamine oxidase A), nicknamed the “warrior gene” because it regulates the calming chemical serotonin in the brain. The neuroscientist discovers that he is the only one in his family without the low-aggression variant of the gene.

The light goes on -- deep organ music -- “I'm a born killer."

However, it’s not science fiction, but the real life story of Dr Jim Fallon, of the University of California-Irvine. Why isn’t he a killer, then? Dr Fallon speculates that brain patterns and genetic makeup are not enough: a childhood of abuse or violence is needed to top up the toxic mix.

This intriguing story attracted many scathing comments on the NPR website. One contended that the genes and the scans hadn’t lied at all: “it's intriguing to consider that in this case the gene for 'sociopathy,' led to tenure.” ~ NPR, June 29