Biological explanations: genetic + neural

• Offenders


  Inherit a gene/ combination of genes, that predispose them to commit crime
• Twin and Adoption studies

  • Karl + Christiansen - studied over 3500 twin paris in Denmark
  • Found concordance rates for offender behaviour of 35% for identical twins (MZ) males + 13% for non-identical twin (DZ) males
  • Included all twins born between 1880 + 1910 in a region of Denmark
  • Offender behaviour was checked against Danish police records
  • Data shows that is' not just the behaviour that might be inherited but the predisposing traits
• Crowe - adopted children

  • Biological mother had a criminal record had a 50% risk of having a criminal record by the age of 18
  • Biological mother doesn't have a criminal record only had a 5% risk
• Candidate Genes


  • Tiihonen et al - genetic analysis of 800 Finnish offenders
  • 2 genes: MAOA + CDH13 -> associated w/ violent crime
  • MAOA gene regulates serotonin in the brain + has linked to aggressive behaviour
  • CDH13 gene linked to substance abuse + attention deficit hyperactivity disorder
  • Analysis found: 5-10% of all severe violent crime in Finland is attributable to the MAOA + CDH13 genotypes
• Diathesis-stress model


  • If genetics have influence on offending it may also be moderated by the effects of the environment
  • Tendency towards offending behaviour may come about through combination of genetic predisposition + biological psychological trigger E.G, being raised in a dysfunctional environment/ having criminal role models
• Neural explanations


  • Neural differences in brains of offenders + non-offenders
  • Evidence in this area involves individuals with antisocial personality disorder (APD)
  • APD is associated w/ reduced emotional response, lack of empathy for feelings of others + a condition that characterises many convicted offenders
• Prefrontal cortex


  • Raine - conducted many studies of the APD brain, reporting that there are several dozen brain-imaging studies demonstrating that individuals w/ antisocial personalities have reduced activity in the prefrontal cortex, the part of the brain that regulates emotional behaviour
  • Raine + his colleagues - 11% reduction in volume of grey matter in prefrontal cortex of people with APD compared to controls
• Mirror neurons


  • Recent research suggests that offenders w/ APD can experience empathy but they do so more sporadically than the rest of us
  • Keysers - only when offenders were asked to empathise did their empathy reaction activate
  • Suggests APD individuals aren't w/ out empathy, but may have neura 'switch' that can be turned on + off, unlike the 'normal' brain which has the empathy switch permanently on