Killer Genes: Born to Kill?

Was Ted Bundy a serial killer because of his troubled childhood? Was Jeffrey Dahmer a murderer because of his alcohol abuse? Did Aileen Wuornos kill because she was abused as a child? True crime stories and the reasons behind why such atrocities are committed are a source of fascination amongst many of us, but also to many scientists. Studies show there are many things which might increase the likelihood of committing a serious crime, like murder, these include upbringing, drug and alcohol abuse, pre-natal stress and even your genetics.

Twin studies have helped separate the environmental and genetic factors that influence criminal behaviour. One study investigated 3,226 male twins; interestingly, they found that before the age of 15, the environment a person was brought up in had more influence on criminal activity compared to genetic factors. However, after the age of 15, the persons genetics had more of an influence over criminal activity compared to shared environmental factors. By combining the results of many twin studies, scientists have shown that 40-60% of the reason people commit serious crime, are genetic. So which genes are involved?

Genome-Wide Association Studies (GWAS) have been used to analyse large groups of peoples’ DNA to determine whether differences in criminality are associated with differences in their DNA sequence. These studies have shown that criminal behaviour is not predicted by a single gene, but rather the interaction of many genes, expressed in the right social environment. However, there are a select few genes which have been identified, which increased the likelihood of an individual committing a serious crime.

You may have already heard of the MAOA gene, also known as the ‘warrior gene’. This gene creates a protein which speeds up the breakdown of chemicals in the brain, which, in turn, determine mood, thinking, perception and behaviour. In some individuals, a change in DNA sequence of the MAOA gene, causes less of the protein to be produced to break down the chemicals in the brain. This means there will be less control over emotion and behaviour regulation, including inhibiting aggression.  Interestingly, this gene is sex linked, meaning it is only found on the X chromosome. As males only inherit one X chromosome, they are more prone to inheriting the variation of the MAOA gene, as they don’t have a second X chromosome to balance out the effects of the varied MAOA gene, which may explain the gender discrepancy in serious crime.

Overall, it appears that a significant cause of serious crime, including murder, is due to genetics. Although scientists have shown that it is the interacting affect of many genes, expressed in a particular environment, which increase a person’s likelihood to commit a serious crime, some studies have identified single genes which have a significant impact. This raises many ethical questions in the sentencing of people with this gene variant. Is it their fault they’ve committed a crime, if they have a gene which predisposes them to violence? Indeed, in 2010, an Italian judge made legal history by decreasing the sentence of a man accused of murder, after the convict was found to be a carrier of the MAOA genetic variant. Do you think this is right? Well, that question is still being debated today, and governing bodies are no closer to deciding whether your genes exempt you from your actions.

References

https://bsj.berkeley.edu/born-to-kill-the-story-of-serial-killer-genes/

https://www.mirror.co.uk/news/technology-science/science/killers-born-murder-gene-scientists-4528684

https://theneurobiologyofbecomingaserialkiller.wordpress.com/2019/11/18/genetic-influences/

https://www.theguardian.com/science/2016/sep/28/natural-born-killers-humans-predisposed-to-study-suggests

https://www.jax.org/news-and-insights/jax-blog/2015/december/the-genetics-of-violent-behavior

https://filmdaily.co/obsessions/true-crime/killer-genetics-doc/

https://www.themakingofaserialkiller.com/genetics

 

Disclaimer

The information in this blog is for information and entertainment purposes only. I am not a medical professional, so I have never and will never give medical advice in this blog. You should always speak to a healthcare professional about your unique health needs. My opinions are entirely my own and do not reflect the organisations or people I work for. I only discuss published literature in this blog which are referenced with links.

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