Do serial killers have an extra chromosome?
There is no such thing as a “killer gene”, but research is revealing genetic tendencies towards violent behaviour.
Face of a serial killer. Photo Credit: Curtis John via Flickr [BY-ND-2.0], 2009.
It’s a slippery, discreet mutation, after all we don’t see entire families of serial killers
Parents of children, who have grown up to be serial killers, have reported that their child was markedly different from their other non-violent siblings. Ted Bundy, an American serial killer, kidnapper and rapist, at the tender age of three slipped butcher knives under the covers of his auntie’s bed. “He just stood there are grinned” she reported as he watched on and she repeatedly cut herself trying to get up. Nine-year-old Jesse Pomeroy from Charlestown Massachusetts, sexually tortured seven boys at his school. Three years later he murdered a four-year-old boy, decapitating his head with a blunt kitchen knife. These gruesome and unethical crimes got me thinking about the kind of influences that trigger one to kill. Are serial killers inherently evil, reflections of their environment or unfortunate victims of gene malfunctions?
Cropped image of blood in water. Photo credit: Peter Almay via Flickr [BY-NC-SA-2.0], 2009.
Nature vs. Nurture; bad seeds blossom in bad environments
Environment alone cannot explain deranged behaviour as too many abused and neglected children grow up to be law-abiding citizens. Yoon-Mi Hur and Thomas Bouchard, a professor of phycology conducted a study in 1997, examining the behaviour of 57 pairs of identical twins, 49 pairs of fraternal twins and 90 non-twins who had all been raised in separate households. They evaluated the extent to which heredity influences perceptions of childhood family environment using the Family Environment Scale and Block Environmental Questionnaire. The study revealed a strong link between impulsivity and sensation-seeking behaviour, attributed almost entirely to genetic factors. Both sensation-seeking traits and impulsivity have been found to be higher in drug abusers, delinquents, and serial killers.
Nature vs. Nurture. Photo credit: Frank DeFreitas via Flickr [BY-NC-ND-2.0], 2012.
Chromosomal abnormalities in serial killers
According to Dr Helen Morrison, an American forensic psychologist and writer, chromosome abnormality in serial killers begins to express itself during puberty. Serial killer, Bobby Joe Long has an extra X chromosome, causing him to produce excess amount of oestrogen. During puberty his breasts began to develop causing him a lot of embarrassment and anger. Bobby channelled this anger into raping over 50 women over a thirty-year time period. His crimes escalated killing 10 women over a 10-week period in 1983.
Conversely, serial killer Richard Speck’s had an extra Y chromosome, which his lawyers argued was the cause of his violent crimes. The court found that while an extra Y chromosome seems like a logical explanation for mutant-aggressive behaviour, there is not much evidence that links the X or Y chromosome to the deviant behaviour of serial killers.
Gosavi Gajbe conducted a study looking at the role of chromosomes in criminality. He examined the chromosomes of 140 murders and looked for any abnormalities that may have influenced them to commit their crimes. The study revealed that there was a definite association between the both variables but he concluded that further studies needed to be completed on more recent cases before conclusions could be made.
Cropped image of the inheritance of an extra chromosome.Photo Credit: Paul Studios via Flickr [BY-CC-2.0], 2012.
The thrill of the kill, is the nervous system to blame?
Studies by Newman et al. have revealed that the nervous system of serial killers is considerably different to an average person. Serial killers feel less fear and anxiety. A study was conducted where a group of sociopaths and a group of healthy individuals were provided with four levers and were asked to identify which lever turned a light on. One of the levers gave an electric shock. While both groups identified which lever supplied the electric shock, the sociopaths took much longer to avoid the punishment. This need for higher levels of stimulations makes psychopaths seek more dangerous situations, which had led scientist to believe that it could partly explain their thrill to kill.
Nervous System. Photo Credit: Paul Walker via Flickr [CC-BY-SA-2.0], 2011.
Causes for killing
One cannot explicitly conclude that chromosome abnormalities are the reason for why people commit such malicious crimes. Further research needs to be conducted to come to a definitive answer. I personally think it’s a combination of genetic factors and the environment one is brought up in. However, it’s hard to believe that some people cannot be inherently evil after reading some of the gruesome acts they have committed.
What do you think? Are serial killers inherently evil, reflections of their environment, unfortunate victims of gene malfunctions or is there a more complex formula that incorporates all of the above?