Genetic and Neural Explanations into offending

• Explain the link between the MAOA gene and criminal behaviour

  MAOA gene has been linked to extreme aggression and violent crime as a mutation of this gene leads to imbalances in neurotransmitters which increases impulsive aggression. This leads to increased impulsive crime and violent crime
• Explain the link between the CDH13 gene and criminal behaviour


  Linked to substance abuse and to ADHD which places people at risk of committing criminal acts
• What supporting evidence is there for the MAOA gene?

  Brunner syndrome is a rare genetic disorder caused by a mutation in the MAOA gene on the X chromosome and was first identified in 1993 in 14 males from a family. All of these males were unable to regulate impulsive aggression, leading to extreme criminal acts. Females were unaffected and males without the mutated gene were normal. This suggests the increased aggression was due to the MAOA gene (nature) rather than nurture
• How does Lange's study support a genetic component to criminal behaviour?

  Studied 13 MZ twins and 17 DZ twins. One of the twins in each pair had spent time in prison. MZ twins, 10 of the co-twins had been in prison compared with only 2 in the DZ twins. This suggests a genetic component to criminal behaviour
• How does Christianson's study support a genetic component to criminal behaviour?

  Studied the concordance rate for criminal behaviour in 87 MZ twins and 147 DZ twins. Found the CCR for MZ twins was 33% and DZ had 12%, which suggests a genetic component to criminal behaviour as MZ share 100% of DNA
• What problems are there with twin studies?

  They cannot be used as a full explanation because if genetics was a full explanation we would expect a 100% CCR. However, in both Lange and Christianson we don't see this, meaning that environmental factors still need to remain as in influence into criminal behaviour, so it is more appropriate to consider a nature and nurture approach (combination)
• Comment on the genetic research with reference to the nature nurture debate

  Genetic research such as twin studies suggests that criminal behaviour may be caused by an interaction between nature and nurture, and this is shown by the diathesis stress model
• What is the diathesis stress model?

  Diathesis stress model suggests a combination of N and N into criminal behaviour. Diathesis = biological factor that predisposes you (MAOA gene for example), Stressor = environmental influences that makes the individual turn to crime (Victim of childhood abuse or having criminal role models)
• How does Mednick's research support the diathesis stress model?

  Checked police records of 13,000 people who had been adopted and their biological and adoptive parents. Found those who's adoptive and biological parents had convictions, 24.5% of the time also had a conviction, just biological, 20%, and no convictions on either side, 13.5%

  Shows criminal behaviour is an interaction between nature and nurture as the highest statistic was when both sides had a conviction.
• What role does the prefrontal cortex have in criminal behaviour?


  Prefrontal cortex - Concerned with impulse control and therefore abnormality in this area may mean a person is less able to control what they do, resulting in criminal behaviour. An aspect of impulse control is control of aggressive behaviour so those with these abnormalities are more likely to commit aggressive crime

  Prefrontal cortex dysfunction is associated with antisocial personality disorder and people with this have reduced emotional responses and a lack of empathy
• What role does the amygdala have in criminal behaviour?

  Criminal behaviour has been linked to reduced amygdala functioning. Amygdala is involved in fear, aggression and social interactions and people with dysfunctional amygdala activity show increased aggression and a lack of fear of the consequences of this aggression, leading to violent and criminal behaviour
• What supporting evidence is there for the role of the prefrontal cortex?

  Raine et al studied 41 murderers who had pleaded not guilty by reason of insanity. Their brain activity was compared to an age and gender matched control group. They found reduced activity or the offender group in the prefrontal cortex and corpus callosum. This supports the idea that a dysfunctional prefrontal cortex can cause criminal behaviour
• What is the problem of Raine et al's research?

  The research is correlational and cannot establish cause and effect. The brain abnormalities could be causing the criminal behaviour or it could be the result of an environmental factor which could also make criminality more likely
• What evidence is there for the role of the amygdala?

  Pardini et al found that 26 year old men with lower amygdala volumes were more than 3 times more likely to be aggressive, violent and show psychopathic traits than compared to men of the same age with normal sized amygdalas
• Comment on neural research with reference to the nature nurture debate

  Nature - Brain scans can show a reduced activity in amygdala and prefrontal cortex functioning, which shows that criminal behaviour is due to genetic deficits at no fault of the individual

  Nurture - An interaction is necessary between biology and the environment in order to trigger criminal behaviour. Professor Jim Fallon had the MAOA gene but never became criminal, showing the biological issues only predispose
• Comment on neural research with reference to free will determinism debate

  Viewing offending behaviour is biologically predetermined is biologically deterministic and if we conclude that physiology is a key part of offending behaviour then there is a question mark over who is criminally responsible. If they are not entirely responsible, then they cannot be punished for their crimes. This also implies that criminals can never fully be rehabilitated if the actions are not a matter of choice