A01 Genetic And Neural Explanations

• Genetic explanation


  suggest that offenders inherit a gene or combination of genes that predispose them to commir crime.
• Twin studies

  Importance of genes illustrated by twin studies. Lange et al investigated 13 identical (MZ) twins and 17 non-identical (DZ) where one of the twins in each pair served time in prison.
• Lange et al findings


  Found 10 of the monozygotic twins but only 2 of the dizygotic twins had a co-twin who was in prison. Thus, the conclustion was that genetics play a predominant part in offending behaviour.
• Adoption studies

  Crowe found that adopted children who had a biological parent with a criminal record had a 50% risk of having a criminal record by age of 18, whereas those whose mother did not have a criminal method, only had a 5% risk.
• Candidate genes


  Tilhonen et al made a genetic analysis of 900 offenders and revealed abnormalities of genes like MAOA ( controls dopaine and sertotonin- link to aggression) and CDH13 (linked to substance abuse and attention deifcit hyperactivity behaviour)
• Tolhonen et al findings

  People with high risk behaviour are 13 times more likely to lead to violent behaviour. But study done on children so cannot be replicated.
• Diathesis stress model

  Tendency towards criminal behaviour may come through a combination of genes and psychologcial/biologcial triggers like the environment for example.
• Neural explanations


  There may be neural differences in the brains of criminals and non criminals. Much evidence comes from investigated individuals diagnosed with antisocial personality disorder.
• Prefrontal cortex


  Raine conducted many studies of the anti social personality brain, where there are several dozen brain-imaging studies showing those with APD have a reduced prefrontal cortex which regulates human behaviour.
• Raine et al findings


  He found an 11% reduction in volume of grey matter of those with APD.
• Mirror neurons


  But some criminals with APD can regardless feel emphathy.
• Keysers et al study


  Keysers et al asked criminals to empathise (to a person experiencing pain on film) their reaction (controlled by mirror neurons in the brain) were activated. Suggests that APD individuals are not totally without empathy but may have a neural switch that can be turned on and off.