The Eternal Question – Is Criminality Genetic, Learned or Both – and does a ‘Criminal’ Gene Exist?


How would you feel if you could predict your likelihood of becoming a ‘criminal’ with a single genetic test?

If such a test was available, would you take it?

It might seem like something out of a science fiction film, but scientists have already made attempts to identify a ‘criminal’ gene.

Dubbed the ‘warrior’ gene, MAOA is the responsible for breaking down serotonin and dopamine – the so-called ‘happiness’ chemicals.

A series of scientific studies have suggested that a tendency towards aggressive and violent conduct can be attributed to a MAOA deficiency.

In 2006, a controversial study was published which attempted to explain the alleged propensity of Maori males to commit violent crimes.

The study suggested that the MAOA gene was carried by up to 61% of all Maori males.

This finding led the project’s head researcher to conclude that, due to their genetic makeup, Maoris ‘are going to be more aggressive and violent and more likely to get involved in risk-taking behaviour like gambling.’

Unsurprisingly, the study roused anger within the Maori community, with members rejecting the findings and expressing concerns that they may further stigmatise already disadvantaged ethnic groups.

A later study conducted in 2009 found that the 2006 study was inconclusive, and that criminal behaviour and aggressiveness were heavily influenced by external factors such as a person’s environment and socio-economic factors including the discrimination suffered by Maori populations following European colonisation.

This view was supported by earlier findings, which suggested that the MAOA gene only had a detrimental impact where the individual had suffered maltreatment as a child.

Accordingly, it commonly accepted within the scientific community that a person’s genetic profile is not solely determinative of a person’s future actions.

But despite the lack of concrete evidence to support the notion of a ‘criminal’ gene and the contention surrounding these studies, there have already been several attempts to use it to explain criminal behaviours.

Back in 1994, in the US state of Georgia, 25 year old Stephen Mobley robbed a Domino’s pizza store.

In the course of the robbery, he pulled out a stolen handgun and shot the store’s night manager, John C. Collins, in the back of the head.

Collins died instantly, and Mobley was convicted of his murder.

Georgia is one of the last remaining US states to retain the death penalty, and Mobley was sentenced to death after just one day of deliberation.

However, in what was perceived as a somewhat radical move, Mobley’s defence team sought to have him excused from the death penalty on the basis of genetic evidence which suggested that he had a disposition towards violent and aggressive behaviour.

Mobley had been described by family members as a difficult child, who exhibited behavioural problems and had a long history of vandalism, assault and animal cruelty.

According to his family, four previous generations of relatives had also displayed similar behaviours and had perpetrated violent and aggressive crimes.

In a desperate bid to spare his life, Mobley’s defence team sought funding to conduct tests for the MAOA gene, arguing that he may have lacked an ability to comprehend the seriousness of his actions if he possessed an MAOA deficiency.

Unfortunately for Mobley, the court rejected this request, arguing that genetic testing at that time was not sufficiently advanced in order to prove a genetic susceptibility towards criminal conduct.

Fast forward to 2007, and it’s a completely different story – at least in Italy.

Abdelmalek Bayout was convicted of stabbing Walter Felipe Novoa Perez to death in 2007, after Perez allegedly insulted his religious eye makeup.

Genetic testing showed that Bayout possessed the MAOA gene, which Italian neuroscientists argued would make him more prone to violent conduct.

This argument was accepted by the Italian court and resulted in a year being knocked off his initial 9 year sentence.

This would appear to be the first time that evidence of a ‘criminal’ gene has been accepted by a court as a mitigating factor in sentencing.

But while the prospect of using genetic predispositions as a basis for having sentences reduced may excite criminal defence lawyers and their clients, it has far-reaching and potentially adverse implications.

The 2006 New Zealand study demonstrates the potential for links between genetics and ethnicity to result in social stigma and promote discrimination.

Other minority groups have also suffered these unintended consequences – for example, various studies have suggested a link between the genetic makeup of Native Americans and alcoholism.

One particular American case detailed a situation in which a judge asked the defendant’s mother about whether she was worried that her daughter would become an alcoholic due to her ethnic background.

This highlights the potential for genetic links to create prejudice, even within the justice system.

And although the 2007 Italian case illustrated the potential for genetic predispositions to result in a more lenient sentence, there are concerns that they could also be used as an aggravating factor, resulting in harsher sentences.

This would be based on the flawed logic that, if someone has a criminal gene, they may pose a permanent risk to the community at large and should therefore be held in custody.

But perhaps the most dangerous consequence of an increased acceptance of genetic profiling is the potential for it to adversely impact government and social policies.

It is commonly accepted that there is a correlation between socioeconomic disadvantage and criminal conduct.

If a particular ethnic group is deemed to be predisposed to violent conduct, it might curb government efforts to address socioeconomic disadvantage, as these groups may be seen as already being ‘genetically predestined’.

Despite these concerns, it is unlikely that any evidence of an individual’s ‘criminal genes’ will be considered by Australian courts anytime soon.

The ‘tendency rule’ says that evidence of a person’s character, reputation, conduct or tendency cannot be admitted in court to prove that a person was likely to have acted in a particular way.

Genetic tests which show a predisposition towards violent conduct would therefore be excluded by the tendency rule, and would not be allowed to be used as evidence in court.


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About Ugur Nedim

Ugur Nedim is an Accredited Specialist Criminal Lawyer and Principal at Sydney Criminal Lawyers, Sydney's leading firm of criminal and traffic defence lawyers.
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