Genetics & Neural Explanations of Offending Behaviour (AQA A Level Psychology): Revision Note

Genetic explanations of offending behaviour

• Genetic explanations of offending behaviour revolve around the idea that criminality is inherited and that there may be specific genes which predispose individuals to criminal behaviour

  • A genetic explanation of criminality assumes that mutations within specific genes or combinations of genes may be a key contributory factor in determining criminal behaviour in an individual

• One way of investigating a genetic explanation of offending behaviour is to use twin studies in which concordance rates are measured to look for agreement between MZ (identical) and DZ (non-identical) twins in relation to criminality, i.e., if one twin has committed a crime, how likely is it that the other twin has also committed a crime?

  • The main assumption underpinning twin studies is that if criminality is genetic, then there will be a higher concordance rate between MZ twins than between DZ twins, as MZ twins share 100% of their DNA

• Lange (1930) conducted the first criminal twin study, investigating 13 MZ and 17 DZ twins where one of the twins in each pair had served time in prison

  • Lange found that 10 of the MZ twins but only 2 of the DZ twins had a co-twin who was also in prison

• Tiihonen et al. (2014) conducted a genetic analysis of almost 900 offenders and found abnormalities in two genes associated with violent crime:

  • The MAOA gene, which controls dopamine and serotonin in the brain

  • The CDH13 gene, which has been linked to substance abuse and ADHD

• Within the Finnish sample, individuals with this high-risk combination were around 13 times more likely to have a history of violent behaviour, although this research is in its infancy and has not so far been replicated

Neural explanations of offending behaviour

• Neural explanations of offending behaviour assume that brain structure and/or neurochemistry increase an individual’s propensity to criminal behaviour

• A neural explanation of criminality assumes that specific neurotransmitters may be a key contributory factor in determining criminal behaviour in an individual

  • E.g., heightened levels of dopamine leading to reward-seeking behaviour 

• Evidence suggests there may be neural differences in the brains of criminals and non-criminals, with much of this evidence focusing on individuals diagnosed with antisocial personality disorder (APD), formerly referred to as psychopathy

  • APD is associated with reduced emotional responses, a lack of empathy for the feelings of others, and is a condition that characterises many convicted criminals

• Structural differences in the brain may also play a role in offending behaviour, particularly concerning the limbic system

  • The limbic system is the area of the brain that helps to regulate emotional responses, particularly the amygdala, which processes emotional information

• Recent research suggests that criminals with APD can experience empathy, but do so more sporadically than the rest of us

  • Keysers et al. (2011) found that only when participants were asked to empathise with a person depicted on film experiencing pain did their empathy reaction, controlled by mirror neurons in the brain, activate

    • This suggests that APD individuals are not totally without empathy, but may have a neural 'switch' that can be turned on and off, unlike the 'normal' brain which has the empathy switch permanently on

• Raine has conducted many studies of the APD brain, reporting that there are several dozen brain-imaging studies demonstrating that individuals with antisocial personality disorder have reduced activity in the prefrontal cortex, the part of the brain that regulates emotional behaviour

  • Raine et al. (2000) also found an 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD compared with controls

Research which investigates genetic & neural explanations of offending behaviour

• Crowe (1972) found that adopted children who had a biological parent with a criminal record had a 50% risk of having a criminal record by the age of 18, whereas adopted children whose mother did not have a criminal record had only a 5% risk

• Brunner (1993) identified a mutation in the MAOA gene, which disturbed the levels of key neurotransmitters such as serotonin, which he linked to the anti-social behaviour and low IQ of a group of males from one family in the Netherlands

Evaluation of genetic & neural explanations of offending behaviour

Strengths

• Mednick et al. (1984) studied over 13,000 Danish adoptees, checking court convictions against police records for each adoptee and their biological and adoptive parents

  • Conviction rates rose from 13.5% when neither set of parents had convictions, to 20% when a biological parent did, to 24.5% when both biological and adoptive parents did, suggesting genetic inheritance matters but environmental influence cannot be disregarded, supporting a diathesis-stress model

• The use of brain imaging techniques such as PET and fMRI provides objective evidence of structural and functional differences, which increases the validity of neural explanations compared with self-report methods

Limitations

• Twin studies typically use small samples, and twins are an unusual sample in themselves so may not represent the rest of the population, e.g., Lange's research was poorly controlled and judgements about zygosity were based on appearance rather than DNA testing

  • Twins also share the same environment, which is a major confounding variable, as concordance rates may be due to shared learning experiences rather than genetics

• Adoption studies are complicated by late adoption, as many children spend much of their infancy with their biological parents and often maintain contact with them afterwards

  • This makes the environmental impact of the biological parents difficult to assess, and Mednick's figures applied to petty offences such as burglary rather than violent crime, so may not generalise to more serious crimes

Issues & Debates

• These explanations focus heavily on biological (nature) factors such as genes (e.g. MAOA, CDH13) and brain structures (e.g. prefrontal cortex, amygdala)

  • This may underestimate the role of environmental influences like upbringing, trauma, or peer pressure, which also contribute to offending behaviour

• These theories are reductionist, as they reduce complex behaviours like crime to simplistic biological causes

  • They ignore the holistic interaction of social, cognitive, and psychological factors in offending behaviour

  • While helpful in identifying risk factors, this approach lacks a full explanation for why crime occurs in specific contexts or why many people with similar biology don't offend