Murderers: Are they Born or Made?

Most people would find it hard to commit murder, but in the backdrop of several high profile homicides in recent times, people are asking loudly what makes some people go ahead and do it.
Neurobiologists identify two types of murderers: those who are hot-headed, aggressive and easily provoked to anger, and another that are cold, calculating, and “psychopathic”, and the two groups seem to differ considerably in the ways their brains function.
The story of taking a peep into the brains of murderers started in the early 1990s when the women of a crime-prone family in the Netherlands approached a neuro-geneticist to look into the brains of their men-folk who had had repeated bookings for violence, arson, rape and murder, to see if there was an evil gene in the family.
And not surprisingly, doctor Hans Brunner who undertook the investigation found that these aggressive men had an abnormal gene located on their X chromosome that encoded for an abnormal subtype of a brain enzyme called MAOA-L (Mono-Amine Oxidase inhibitor of the type A, and the subtype L, for long acting variety) located in the pre-frontal areas of their cortex.
This gene soon came to be called the Warrior Gene as it provided an answer to what made people aggressive and hot headed by causing a change in the metabolism of neuro-transmitters in the front region of the brain.
But this gene left unanswered why some criminals committed murder, not in anger but in cold blood, and did not seem to show excitement or aggression, perhaps like Indrani Mukherjea. Neuro-psychologists realised Warrior Gene could not explain the behaviour of the “cold blooded” psychopaths.
The lead to solving their mystery interestingly came from the brain autopsy of a psychopath who had gone on an unprovoked shooting spree of 30 innocent children in the USA before being gunned down by the police. When his brain was examined post-mortem, pathologists found a “tumorous” vascular swelling in a under-surface region of his brain called the Amygdala.
Neurobiologists soon jumped in on this cue and looked closely at the brains of hardened criminals using functional PET scans They found that convicts who had been charged with heinous crimes such as cold-blooded multiple murders indeed showed abnormalities in the serotonin uptake in Amygdala portion of their brains.
The brain scan pattern of cold-blooded psychopaths show increased activity in the Amygdala region with scant or no activity in the prefrontal cortex, suggesting that the part of the brain that evokes emotion and says “ No. Don’t do it. It is wrong” is suppressed.
The vexing question that now still hangs in the air, is the role of upbringing and childhood experiences in the making of a killer. Scientists feel that while genes load the gun and make some prone to crime, it is the rearing, environment and circumstances that finally help pull the trigger!