It is common knowledge within the world of genetics that many behaviours stem from genetic factors—such as aggression, violence, and those which serve as early implications of crime. I would like to delve deeper into this study of criminology and see what structural and functional features of the brain correlate to violence in individuals. My inquiry for this cycle is "Can people manipulate the biological roots of crime to prevent criminal behaviour in individuals?", but I’ll start off this post with introducing the importance of genetics when it comes to one’s predisposition of crime.
Serial killer, Jeffery Landrigans, was a man whose criminal career started at a young age. He was adopted as an infant (after being abandoned by his parents) into a well-educated home where he was raised by an affectionate mother, a respected geologist for a father, and their biological daughter. Despite living in such circumstances, Landrigans began abusing alcohol and drugs, hardly attended school, and got arrested for burglary at the age of 11. He later got arrested for murder, escaped jail in Oklahoma seven years later, and ran off to Arizona where he strangled his second victim. It was on death row when an inmate noticed his uncanny resemblance to Darrel Hill, another criminal on death row in Arkansas. It turned out Hill was Landrigan’s biological father whose criminal career also started at a young age. Eerily enough they both were responsible for two murders and had escaped prison after their first conviction. Furthermore, Hill’s father had also been a delinquent! Landrigan’s story heavily implies that there is a genetic foundation for crime and that individuals may be “born” criminal.
The significance of genetics when it comes to the likelihood of one’s engagement in crime cannot be ignored. In Sweden, a large study combining adoption data and police register data proved that violence is more likely to occur in adoptees with a biological parent convicted of crime than adoptees who have non-criminal biological parents. A study conducted by Sarnoff Medick in Denmark demonstrates how the increasing number of offences in biological parents increases the likelihood of their sons being convicted.
Another field of research crucial to understanding how genetics plays a role on potential criminals are twin studies. Everyone shares 99% of genes. Identical twins share 99% of that 1% gene variation that differentiates people. So if we disregard environmental variations, identical twins should mature and live very similarly to each other. University professors Adrian Raine and Laura Baker teamed up and conducted a twin study consisting of 1,210 (both fraternal and identical) twins from Southern California. They assessed the twins and their caregivers, and presented them with a checklist of behaviours, including antisocial ones. They also gave these checklists to the twins’ teachers. From these measures of antisocial behaviour, they estimated the heritability of antisocial behaviour in these children. Results were that genetics contributed from 40% to 50% of the antisocial behaviour the children’s caregivers, teachers, and they themselves analyzed. In fact when the informants’ sources were averaged out, the professors discovered that the percentage increased to an astonishing 96%! These behaviours are indeed predominantly heritable!
From all this research, it is safe to say that genetics does have an impact on one’s possibility of committing crime and displaying antisocial behaviour. It is good to note that environmental factors also do play a significant role (think about 50/50 in some cases)! But what about proactive forms aggression and repeated acts of violence? What about those with a defective gene or two that may ignite violence? I will be compiling this research in my future posts. Thank you for reading, and please feel welcome to leave your responses!
Farahany, Nita A. The impact of behavioral sciences on criminal law. Oxford University Press, 2009.
Raine, Adrian. The anatomy of violence: the biological roots of crime. Penguin Books, 2014.
Mednick, S A, et al. “Genetic influences in criminal convictions: evidence from an adoption cohort.” Science (New York, N.Y.)., U.S. National Library of Medicine, 25 May 1984, www.ncbi.nlm.nih.gov/pubmed/6719119.
Baker, Laura A., et al. “Genetic and Environmental Bases of Childhood Antisocial Behavior: A Multi-Informant Twin Study.” Journal of abnormal psychology, U.S. National Library of Medicine, May 2007, www.ncbi.nlm.nih.gov/pmc/articles/PMC1913189/.
Baker, Laura A., et al. “The Southern California Twin Register at the University of Southern California: II.” Twin research and human genetics : the official journal of the International Society for Twin Studies, U.S. National Library of Medicine, Dec. 2006, www.ncbi.nlm.nih.gov/pmc/articles/PMC1913188/.