Bio Explanations

• Koenig (2014) found abnormalities in the OFC correlated with psychopathy.
• The OFC can affect the amygdala.
• Candidate genes: MAOA gene: Brunner et al (1993) analysed the DNA of a Dutch family with 8 male members who had histories of impulsive and violent crimes and found they shared a gene for low MAOA.
• Diathesis stress: Epigenetics proposes that genes are switched on by epigenomes, which are in turn affected by environmental factors, e.g. maltreatment in childhood.
• XXY Syndrome: Extra Y chromosome affects 1 in 1000 people and doesn’t affect testosterone.
• Symptoms of XXY Syndrome include being taller, having more acne, and having lower intelligence.
• Impulsive and behavioural difficulties are potential symptoms of XXY Syndrome, which could lead to crime as individuals may be picked on for appearance, more impulsive, and may be less likely to think through the consequences.
• Jacobs et al (1965) conducted a chromosome survey of male prisoners in Scotland and found that XYY patterns were over-represented (15 per 1000).
• Re and Birkhoff (2015) conducted a meta analysis and found no link between XYY and offending over 50 years.
• Prevalence in prisons may be linked to social factors such as inability to fit into society and find work.
• Only affects men and only 1 in 1000, so cannot explain all crime.
• Acquired brain injuries (ABIs), especially sustained in childhood, are linked to offending.
• ABIs can disrupt development, especially in the prefrontal cortex (impulse control), which is the last to develop.
• ABIs can destabilise mood, concentration and decision making, which could make offending more likely (still only a predisposition).
• Williams et al (2010) found that 60% of 196 inmates in a UK prison recalled one or more head injuries in their youth.
• Abnormalities in the amygdala have been associated with psychopathy, which is characterised by features such as narcissism, fearlessness, emotional detachment, grandiose sense of self worth, lack of remorse or guilt.
• Williams et al (2010) argued for standardised screening of young people when they first offend.
• Raine et al (1990) investigated fear responses in 1,795 3 year olds, and found that those who went on to commit crime were less likely to exhibit fear when the first tone was played, due to abnormal amygdala functioning.
• Raine et al (1997) found differences in the prefrontal cortex, more activity in the right amygdala, less in left amygdala.
• Individual differences in the amygdala have been investigated, with conflicting research into gender differences.
• The amygdala explanation is reductionist, as it explains crime in terms of simple biological features, which obscures a deeper meaning of crime.
• Charles Whitman, a spree killer, had a brain tumour pressing on his amygdala, which can lead to crime because people may be more reactive (fight or flight).
• Neural injury should be the same as mental illness in court, so punishment should be reduced because of less responsibility.
• The amygdala is part of the limbic system and correlates with emotion, especially aggression.
• Correlation is not cause, as other areas of the brain may be implicated, for example the orbitofrontal cortex in the frontal lobe is thought to regulate self control and reduced functioning is associated with violent outbursts.