It’s a question which has been poured over for centuries. What possesses a person to kill again and again? Only a tiny proportion of killers are prolific, with many murders falling under the category of “crime of passion”. However, scientists are now beginning to build a new understanding of what drives these individuals to kill again.
A new infographic provided by Best Counseling Degrees summarises patterns, traits and statistics – and sheds light on what makes a serial killer. According to the infographic, Chicago-based forensic scientist Dr Helen Morrison has interviewed 135 serial killers and believes many have an extra X chromosome in their DNA.
By way of example, Bobby Joe Long – who is currently on death row in Florida – has this extra chromosome. In Long’s case, his body produced an excessive amount of oestrogen causing him to grow breasts, leading to him becoming angry and ashamed. Richard Speck, a serial rapist and murderer, also had an extra chromosome but in his case, it was the Y chromosome.
Furthermore, University of California Professor Jim Fallon (not to be confused with Jimmy Fallon) discovered that a certain gene called the MAO-A gene, also known as the “warrior gene”, makes people more predisposed to psychopathy.
However, Dr Fallon is a neuroscientist by trade rather than a geneticist. By studying active brains, he discovered that low activity in the frontal lobes also correlates with psychopathy. Furthermore, when investigating his own genetic and neurological makeup, he discovered that he and members of his family showed both of these traits. So why is he not a killer? Speaking to the Guardian, he Dr Fallon explained:
“Why, in the light of the fact I have all of the biological markers for psychopathy, including a turned off limbic system, the high risk genetic alleles, and the attendant behaviours, including well over half of those listed in the psychopathy tests and low emotional empathy, did I turn out to be a successful professor and family man?
One most likely reason is that although I have the genetic makeup of a “born” psychopath, some of those very same “risk” genes in someone showered with love (versus abuse or abandonment), from childbirth through the critical first few years of life, appear to offset the psychopathy-inducing effects of the other “risk” genes.”
As it often does, this comes down to the old argument of nature versus nurture. But here, it seems, it comes down to both. In most cases, those predisposed to psychopathy will never kill. However, Fallon proposed that when one of these individuals does act upon their impulses, a traumatic experience will usually have acted as a trigger.
Childhood trauma, isolation and social alienation often play a huge part in the making of a murderer. That said, there seems to be something innate in a serial killer. David Berkowitz, who shot dead six people in the late seventies, puts it best; “I am on a different wavelength then everybody.”