Name: Kyle Rees
Student Number: n8545332
Tutor: Colleen Niland

Nature vs. Nurture

Will MAOA, the Next Witness, Resume to Stand


Tac, L (2009)

The artefact chosen explores the physiological determinants that may predispose criminal behaviour, and more importantly, highlights the implications. The image solely focuses on the 'nature' side of criminals rather than the 'nurture'. In 1961, scientists discovered the first man carrying the XYY 'extra' chromosome (Horan, S, 1992). At the time, there was reason to believe that there was a link between aggressive behaviour with men carrying XYY. Over the next couple of years, there was a significant increase in the incidence of men with the chromosome, even know there was no evidence to estimate the exact occurrence. This discovery, at the time, gave the criminals an almost 'free pass' out of jail.

Since then, the focus has been taken off the XYY genetic defect as studies show a less likelihood of linkage to behaviour alone, and shift towards MAOA (monoamine oxidase A). A large amount of studies are suggesting a strong correlation between MAOA (the enzyme responsible for engulfing serotonin) and aggression in criminals (Gendreau, P, Perusse, D, 2005). The artefact implies that MAOA is 'the new' XYY. It conjures up the questions; can we 'blame' a predisposing determinant and disregard free will? And if so, is there going to be a 'new' MAOA in the future?

Public Health Issue

This wiki presentation will focus on the physiological determinants, as well as social, in relation to crime, and how it ultimately impacts population health. Specifically, some key health issues include:
(1) The social and ethical implications for having genetic and chemical predisposing factors.
(2) The justification of genes, should this change how criminals are punished?
These issues are fundamental in the context of population health. The literature review and cultural and social analysis will explore the need and importance of these health issues.

Literature Review

There has always been an ambiguous nature surrounding who, or what is responsible for criminal behaviour. Large amount of studies suggest that there is not one underlining factor that predisposes an individual to criminal behaviour (Gendreau, P, Perusse, D, 2005). To be able to analyse if a predisposing factor correlates to criminal behaviour, we have to focus on the development of aggression. It was stated that aggression in criminals can be recognized by a combination of biological and non-biological factors (Israel, Salomon, Ebstein, Richard P, 2001). Gendreau, P, Perusse, D (2005) imply that one gene alone, unaffected by environmental influences, cannot directly link to aggression in criminals. Instead, it is a combination of genetic and interactive environment factors.

Monoamine oxidase A (MAOA)has been the focus of numerous genetic studies in relation to aggression. The enzyme is responsible for metabolizing hormones such as adrenaline, dopamine and serotonin (Chen, K, et. al. 2004). Research by Gendreau, P, Perusse, D, (2005) indicates that there is a strong link between low levels of MAOA and impulsive aggression. Specifically, a study by Frazzetto, G, et. al. (2007) which included 235 men, measured the levels of MAOA and the exposure to early life trauma. The results revealed that men with low levels of MAOA, including early life exposure to a traumatic event, produced much higher rates of physical aggression. The table below, adapted by Caspo et al. (2002), compares levels of MAOA and maltreatment and associates a relative risk. It is shown that a combination of low MAOA and maltreatment has the highest risk factors of violent offenses.


Further studies have examined people with a rare, mutated MAOA genome, called Brunner syndrome. Only a few men were closely studied and were urine tested over 24 hours to measure the low levels of MAOA (Brunner, H, Nelen, M, 1993). The types of behaviors associated to the men with this syndrome included impulsive aggression, attempted arson and rape. Although this study contained few men, and was not current, in recent years, other studies also suggest a strong correlation between MAOA deficiency and impulsive aggression (Gendreau, P, Perusse, D, 2005).

Case Study
Abdelmalek Bayout


In 2007, Abdelmalek Bayout admitted to the stabbing and killing of a man in Italy. During the midst of the trial, Bayouts lawyer asked that a mental illness of his client to be taken into account. The judge sentenced Bayout to 9 years and 2 months in jail, 3 years less for a sound minded person. In 2009, Bayout was allowed genetic testing by scientists in an attempt to re-evaluate the case. The tests came back with abnormalities in the levels of MAOA in Bayout's system. In light of this new evidence, the court decided to reduce a further year off his time in prison (Feresin, E, 2009). The case stirred questions about whether genes can absolve the responsibility of crime. Other court cases have had similar outcomes in the evaluation of genes. The table shows the level of MAOA recorded in previous crimes. A level of 3-3.5 MAOA relates to a low level.

Capsi, et al (2002)



Levitt, M, Manson, N (2007) argues that a criminal that poses the genetic condition should be treated accordingly and not just put in jail. Capsi, et al (2003) suggests that appropriate pharmaceutical treatment could be available, although, only in children that have had exposure to trauma and have low levels of MAOA. The study also shifts focus towards family interventions at a lower cost. However, this was then discussed to be difficult due to other factors such as socioeconomic status, poverty and stigmatisation.

The testing methods for MAOA would prove to be complex and open up ethical issues due to the environmental and social influences (Levitt, M, Manson, N (2007). The testing would be based on social groups, age, sex, as well as social criteria. The National Human Genome Research Institute (2012) questions if this genetic testing is brought in more readily, should babies be screened to determine the chance of that they might posses criminal aggression.

Levitt, M, Manson, N (2007) used the analogy of a hereditary 'ear wriggle' to highlight a public health issue. They explain that just because an individual has the ability to do so, does not mean they have to. Additionally, the hereditary 'ear wiggling' does not tell us why they do so at a specific time. This also applies to genetic MAOA predisposing deficiency. On the other hand, another issue Levitt, M, Manson, N (2007) emphasized was that people with MAOA deficiency do not choose to have it. Consequently, individuals should not be held responsible if the 'genome' caused the crime. The research then compares this situation to people who were brought up in a low socioeconomic home or poverty without choice. The argument remains relevant as Levitt, M, Manson, N (2007) explains that these individuals should not be held responsible for the crime because technically it was the inevitability of growing up in a disadvantaged environment.

Social and Cultural Analysis
To avoid criminal responsibility, defendants will attempt to shift the blame of the crime on a predisposition, opposed to free will (Bernet, W, 2007). Consequently, questions arise from a fairness point of view. A famous philosopher and founder of classical liberalism, John Locke, explored the idea of 'Tabula Rasa' or a 'blank slate'. His theory implies that everyone is born 'blank' and ready to be filled with knowledge. In other words, everything that an individual is characterised by, behaviour, personality and thoughts are all a result of nurture. This was the acceptable view from early 17th century and even at present.

Some other recent theories include population heterogeneity and labelling. For the population heterogeneity theory, Hansmann, H, (1982) compares statistical data to find trends with homicide rates in heterogeneous cultural groups. His studies showed that there was an increase in ho micide rates in these communities. Some other theorists believe that if a person is labelled as a criminal, they are more likely to participate in criminal activity. Loeber,R, et. al, (2005). These theories from past to present reveal how societies may view this issue. Different cultures and religions may disregard genetic basis for criminal activity and solely base it on the environment. Individuals brought up in lower socioeconomic groups may endure stigmatisation as a result.

Firstly, the focus should consist of finding out the extent of behavioural issues relating to genetic defects. Secondly, health professionals should properly address the issues associated such as discrimination and stigmatisation. Finally, finding out the most ethical and appropriate treatment, this could include interventions and medications.


The artefact not only explores genentic relevance in criminals, it also highlights the problems associated with shifting responcibility. This presentation has emphasised other important factors influencing criminal behaviour, not only from a nurture point of view. It is a complex issue to examine due to the many ethical and social repercusions of absolving criminal behaviour.

This presentation has given me another perspective on the way influences can effect individuals. Not by just looking at the normal trends in relation to nature vs. nurture, but looking outside the box has lead me to a deeper understanding of the fundemental issues often ignored.

Wiki Page Discussion (1)
This presentation revealed another side of the highly debated topic surrounding female athletes. The artefact chosen was an appropriate perspective, the mothers, of her daughters controversy. The wiki highlighted how much the media influences these issues and the problems that come along with it. Well written and argued.

Wiki Page Discussion (2)

This wiki presentation used a good artefact to show the medias perspective of bogans. It also emphasised the public health issues such a living in a low socioeconomic community and the repercussions. There was also a good point on stigmatisation of bogans, how they are perceived in the general community as 'nothing but trouble'. Addressing issues such as poverty by implementation of better education opportunities. Good presentation in making aware that bogans are not just your classic 'laid back' person and that poverty is an issue that needs addressing.

Horan, S (1992), The XYY Supermale and the Criminal Justice System: A Square Peg in a Round Hole, 25 Loy. L.A. L. Rev. 1343(1992),

Hansmann, H, (1982), Population Heterogeneity and the Sociogenesis of Homicide: Social Forces, 61:1, September, 1982

Brunner, H. Nelen, M. (1993). Abnormal behaviour associated with a point mutation in the structural gene monoamine oxidase. Science, 262, 578-580.

Caspi, A. Mclay, J, Moffitt, T, Mill, J, Martin, J, Craig, I. W, Taylor, A, (2002). Role of genotype in the cycle of violence in maltreated children. Science, 297, 851-854

Gendreau, P, Perusse, D (2005). The Developmental Origins of Aggression: Genetics and the Development of Aggression. Chapter 3, p223-235.

Chen, K., Holschneider, D.P., Wu, W., Rebrin, I., Shih, J. (2004) A spontaneous point mutation produces monoamine oxidase A/B knock-out mice with greatly elevated monoamines and anxiety-like behavior. Biol. Chem.

Frazzetto, G, Di Lorenzo, G, Carola, V, Proietti, V, Sokolowska, E, Siracusano, A, Gross, C, Troisi, A, (2007). Early Trauma and Increased Risk for Physical Aggression during Adulthood: The Moderating Role of MAOA Genotype. 2(5): e486. Published online 2007 May 30. doi: 10.1371/journal.pone.0000486

Levitt, M, Manson, N (2007). My Genes Made Me Do It? The Implications of Behavioural Genetics for Responsibility and Blame. Health Care Anal. Mar;15(1):33-40.

Bernet, W, Cindy, L, Jones, V, Farahany, N, Montgomery, S, (2007). Bad Nature, Bad Nurture, and Testimony regarding MAOA and SLC6A4 Genotyping at Murder Trials.J Forensic Sci,November 2007, Vol. 52, No. 6. doi: 10.1111/j.1556-4029.2007.00562.x

Loeber, R, Lacourse, E, Homish, L (2005). The Developmental Origins of Aggression: Homicide, Violence and Developmental Trajectories. Chapter 10, p202-219.