Biological explanations: genetic and neural

• Genes


  Consist of DNA strands
• DNA


  Produces instructions for general physical features of an organism (such as eye colour, height) and also specific physical features (such as neurotransmitter levels and size of brain structures)
• Physical features


  May impact on psychological features (such as intelligence and mental disorder)
• Genes

  Are transmitted from parents to offspring, i.e. inherited
• Neural explanation

  Any explanation of behaviour (and its disorders) in terms of (dys)functions of the brain and nervous system
• Neural explanation

  • Includes the activity of brain structures such as the prefrontal cortex, and neurotransmitters such as serotonin and dopamine
• genetic explanation - twin studies

  • Christiansen - 3500 twin pairs in Denmark - found concordance rates for offender behaviour of 35% for MZ males and 13% for DZ male
  • offender behaviour was checked against Danish police records
  • indicates that it is not just the behaviour that might be in herited but the underlying predisposing traits
• genetic explanation - adoption studies

  • Crowe - adopted children whose biological mother had a criminal record had a 50% risk of having a criminal record by 18
  • adopted children whose biological mother didn't have a criminal record - 5%
• genetic explanation - candidate genes

  • Tiihonen - 800 Finnish offenders - suggested that two genes may be associated with violent crime
  • MAOA gene - regulates serotonin in the brain and has been linked to aggressive behaviour
  • CDH13 gene has been linked to substance abuse and attention deficit hyperactivity disorder
  • 5-10% of all violent crime in Finland is attributable to these genotypes
• genetic explanation - diathesis-stress model

  • a tendency towards offending behaviour may come about through the combination of genetic predisposition and biological or psychological trigger
  • dysfunctional environment or criminal role model
• AO3 - genetic explanation - strength

  P: support for the diathesis-stress model of offending

  E: Mednick - 13,000 Danish adoptees offending rates

  biological nor adoptive parents had convictions - 13.5% ppts did

  biological parent had conviction - 20% ppts did

  both biological and adoptive parents had convictions - 24.5% ppts did

  L: genetic inheritance plays an important role in offending but environmental influence is clearly important
• AO3 - genetic explanation - limitation

  P: using twin studies as evidence assumes equal environments

  E: assumed environmental factors are held constant because twins are brought up together and therefore must experience similar environments

  applies more to monozygotic twins - look identical and treated similarly

  L: higher concordance rates for MZ in twin studies may simply be because that are treated more similar than DZ twins
• Neural explanations

  • prefrontal cortex
  • mirror neurons
• neural explanations

  • antisocial personality disorder
  • reduced emotional responses, lack of empathy
• neural explanations - prefrontal cortex

  • Raine - conducted studies of the APD brain
  • antisocial personalities have reduced activity in the prefrontal cortex - regulate emotional behaviour
  • Raine found an 11% reduction in the volume of grey matter in the prefrontal cortex
• neural explanations - mirror neurons

  • Keysers - only when offenders were asked to emphasise did their empath reaction activate
  • APD individuals are not totally without empathy but may have a neural switch that can turned on and off - unlike normal brain which is always on
• AO3 - neural explanations - strength

  P: support for the link between crime and the frontal lobe

  E: Kandel and Freed - reviewed evidence of frontal lobe damage and antisocial behaviour

  People with such damage tended to show impulsive behaviour, emotional instability and an inability to learn from their mistakes - frontal lobe associated with planning behaviour

  L: supports the idea that brain damage may be causal factor in offending behaviour
• AO3 - neural explanations - limitation

  P: link between neural difference and APD may be complex

  E: Farrington - studied a group of men who scored high on psychopathy these individuals had experienced various risk factors during childhood

  These early childhood experiences caused APD and also some of the neural differences associated with it - reduced activity in frontal lobe

  L: this suggests the relationship between neural differences, APD and offending is complex and there are other variables that have an impact