Genetic Explanations

• Genetic explanations of offending behaviour suggest that ‘would-be’ offenders have inherited a gene, or combination of genes that predispose them to commit crime.
• Twin studies are conducted to identify a genetic basis of behaviour. By examining monozygotic (identical) twins and dizygotic (non-identical) twins (who share 100% and 50% of their genetic make-up respectively), concordance rates (i.e. percentages to show how many twin pairs share the behaviour under observation) can help to indicate a possible genetic tendency.
• Christiansen (1977) examined over 3,500 twin pairs in Denmark and identified concordance rates of criminal behaviour
• What were the finding of Christiansen's twin studied?

  It was found that concordance rates were higher in male MZ and DZ twins compared to female twins.

  • Male MZ twins = 35%
  • Male DZ twins = 13%
  • Female MZ twins = 21%
  • Female DZ twins = 8%
• What do christiansen's findings from his twin study indicate?

  The findings indicate a degree of inheritance; that the criminal behaviour is inherited but also the underlying predisposing traits.
• Crowe (1972) compared a group of adopted children whose biological mother had a criminal record, to a control group of adopted children whose biological mother did not have a criminal record.
• Crowe's (1972) findings:

  It was found that if a biological mother had a criminal record, 50% of the adopted children also had one by the time they were 18. In the control group, only 5% of the adopted children had a criminal record by the time they were 18.

  This suggests that regardless of the changed environment, children seemed biologically predisposed to criminality.
• Neural explanation:

  An alternative way of looking at the biological causes of offending behaviour is to examine neurochemical (neurotransmitters) and neurophysiological underpinnings.
• Neural explanation - neurochemistry:

  Serotonin – this neurotransmitter has been linked to mood and impulsiveness. Several studies have reported a link between low levels of serotonin and aggression linked to criminal behaviour. Lots of offenders are also diagnosed with antisocial personality disorder (APD), characterised by reduced emotional responses, a lack of empathy for the feelings of others. This would suggest a link between offending behaviour and low levels of serotonin.
• Neural Explanation - Neurophysiological:

  There is an indication that offenders (specifically violent offenders) have abnormal brain function when compared to normal controls.
• Neural Explanation - Neurophysiological:

  Research by Raine et al (2000) identified a relationship between people with APD and reduced activity in the prefrontal cortex area of participants’ brains, which regulates emotional behaviour, evidencing an 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD compared to controls.
• Neural Explanation - Neurophysiological:

  Rain's research on people with ADP and it's link with reduced activity in the prefrontal cortex followed earlier research by Raine et al (1997) in which reduced activity in the prefrontal cortex and corpus callosum was found in 41 offenders convicted of murder or manslaughter.
• What would the reduced activity in the prefontal cortex (Raine et all - 2000) suggest?

  As there is largely reduced activity, it would suggest that the brains of offenders are slowed and perhaps unable to make the swift decisions to react appropriately in certain situations. For example, the frontal lobes are linked to planning behaviour; therefore, perhaps the decreased prefrontal cortex activity indicates that offenders are unable to consider the consequences of their actions and control their behaviour.
• Neural Explanation - Mirror Neurons:

  Mirror neurons are a type of sensory-motor cell located in the brain that are activated when an individual performs an action or observes another individual performing the same action. Thus, the neurons “mirror” others' actions.
• Neural Explanation - Mirror Neurons:

  More recent research has suggested that offenders can feel empathy but they do so more sporadically than others and may need prompting to do so. Keysers (2011) found that only when offenders were asked to empathise (with a person depicted on film as in pain) did their empathy reaction became active. This suggests that individuals with APD are not totally without empathy but that there is a neural switch that can be turned on and off (unlike the ‘normal’ brain where the empathy switch is permanently on).