The Horizon programme ‘Are you good or evil?’, shown on BBC2 on Wednesday evening challenges traditional understandings of free will and human responsibility.

The question asked by the programme was not so much ‘Are you good or evil?’, as ‘why are some people good and some people evil?’ Why do some people go out of their way to help their fellowman while others kill and maim without any feeling of guilt or remorse?

The programme featured a number of scientists who have been exploring the chemical basis of morality in different contexts – from the neurochemistry that balances aggression with co-operation in football players, to the genetic makeup and resulting brain structure of psychopaths. And it turns out that at least some of the personality traits that make people evil are biological.

Prof Bob Hare, after working as a psychiatrist in a high security prison in Vancouver, began researching the phenomenon of psychopathology after encountering people who he reluctantly admits could only be described as evil. He took brain scans of many serial murderers and found that they all had certain common features. This included abnormalities in the orbital cortex and the front of the temporal lobe which includes the amygdala. This is part of the limbic system which is responsible for emotions and motivation, and controls impulsivity.

The next challenge was to find the genetic basis for this aberrant brain structure. A ‘low activity’ variant of a particular gene, common to psychopaths, was discovered. It became known as the ‘warrior gene’.

A neuroscientist from California, Jim Fallon, decided to take brain scans and examine the genes of his living relatives, as well as his own, because there had been sixteen murders committed by one branch of his family. To his surprise and consternation, his was the one brain scan and set of genes that contained the psychopathic aberration.

He then wondered why he had not become a criminal and came to the conclusion that it was because he had been blessed with a very happy childhood. Whether people actually exhibit psychopathic behaviours, then, depends not only on their genetic make-up, but on what happens to them in childhood. Those who have the ‘warrior gene’ and associated brain structure and also suffer abuse or neglect in childhood are much more likely to become criminals.

The programme ended with the provocative question: “Whether we are good or whether we are evil lies partly in our genes and partly in our environment; and as we don’t choose either, are we really free to choose at all?”

The question of free will is one that has engaged Christians as well at different times. The great theologian, John Calvin, was convinced that our wills are so bound to do evil that we are not even free to choose God unless He first chooses us. And indeed, Jesus said to his disciples, “You did not choose me, but I chose you….” (John 15:16)

Be that as it may, we are reminded once again, how wrong it is to stand in judgement on our fellowmen. There, but for the grace of God…