genetic and neural explanations

• genetic explanation

  suggests offenders inherit a combination of genes that predispose them to commit crime
• lange - twin studies


  investigated 13 identical (MZ) twins and 17 non identical (DZ) where one of the twins in each pair had served time in jail

  • found that 10 of the MZ twins but only 2 of the DZ twins had a co-twin who was also in prison
  • concluded that genetic factors must play a predominant part in offending behaviour
• crowe - adoption studies


  found adopted children who had a biological parent with a criminal record had a 50% risk of having a criminal record by 18

  • whereas adopted children whose mother didn't have a criminal record only had a 5% risk
• tikonen - candidate genes

  did a genetic analysis of 900 offenders that had abnormalities on specific genes that may be associated with violent crime

  1. MAOA gene - controls dopamine and serotonin in brain, has been linked to violent behaviour
  2. CDH13 - has been linked to substance abuse and ADHD

  individuals with this high risk combination of genes were 13 times more likely to have a history of violent behaviour

  • X but this research hasn't been replicated - unreliable and invalid?
• diathesis stress model - influence of genetics on offending can also be affected by the effects of the environment

  the combination of genetic predisposition and biological/psychological triggers can help influence the tendency of criminal behaviour

  • eg. being raised in a dysfunctional environment or having criminal role models
• MAOA gene associated with an increase in aggressive behaviour - referred to as the warrior gene
• A mutation in the MAOA gene results in a deficiency in the biochemical use of neurotransmitters such as serotonin and dopamine
• Research has shown that people with low activity from the MAOA gene displayed higher levels of aggression than individuals with high activity from the MAOA gene
• neural explanation


  focuses on areas of the brain and nervous system, and the action of neurotransmitters.
• Irregularities in levels of neurotransmitters – being linked to violence/offending ?

  • high levels of noradrenaline – violence and aggression
  • low levels of serotonin – greater impulsivity and low moods
  • dopamine indirectly linked with the role addiction (due to being rewarded)
• neurophysiological reasons?

  • Reduced frontal lobe (older region of the brain, seen as a survival benefit) volume in people with anti-social personality disorder
  • Reduced activity in the pre-frontal lobe cortex (which is higher-level thinking) which controls emotional behaviour (Raine 2000)
• individuals diagnosed with antisocial personality disorder(APD) investigated for neural differences

  • APD is associated with reduced emotional responses, a lack of empathy for the feelings of others - a condition that characterises many convicted criminals
• prefrontal cortex - raine conducted studies of APD brain


  reported several brain imaging studies demonstrating that individuals with anti social personalities have reduced activity in the prefrontal cortex (regulates emotional behaviour)
• mirror neurons - keysers et al found that when criminals were asked to emphasise with a person in a film experiencing pain, their empathy reaction, which is controlled by mirror neurons, activate


  suggests that APD individuals are not entirely without empathy

  • they may have a neural 'switch' that can be turned on and off - unlike the 'normal' brain which has the empathy switch permanently turned on
• X twin studies are an 'unusual sample' and don't represent the rest of the population
• X twin reared in same environment = confounding variable

  • concordance rates may be due to shared learning experiences rather than genetics
• X biologically reductionist

  • reducing offending behaviour down to genetic and neural issues
• X reducing the cause of criminal behaviour down to it running in families makes it difficult to disentangle the effects of genes and neural influences from other possible factors - karz et al
• X biologically deterministic - people claiming they were not acting under their own free will raises ethical questions about what society does with people who are suspicious of carrying criminal genes
• X late adoption complicates the presumed separation of genetic and environmental influences
• TICK mednick et al - study of 13000 danish adoptees


  13.5% adoptees criminally convicted, but neither biological/adoptive parents had any convictions

  figure rose to 20% when either of the biological parents had convictions

  figure rose again to 24.5% when both adoptive and biological parents had convictions

  • suggests that genetic inheritance plays an important role in offending and environmental influence cant be disregarded
  • supports diathesis stress model of crime