Forensics - Genetic explanations

Question 1

Outline what is meant by genetic explanations of crime

Answer 1

Genetic explanations suggest that particular genes, or combinations of them, are associated with criminal behaviour.

Question 2

Outline evidence supporting genetic explanations of crime

Answer 2

• Johannes Lange (1930)
• Investigated 30 MZ twins and 17 DZ twins
• One of the twins in each pair had served time in prison
• 10 MZ twins and 2 DZ twins had co-twin who was also in prison
• Suggests genetic factors must play an important part

Question 3

Outline research into candidate genes for genetic explanations of crime

Answer 3

• Tiihonen
• 900 offenders / Finnish sample
• Revealed abnormalities on 2 genes that may be associated with violent crime
• MAOA gene – controls dopamine and serotonin in the brain, linked to aggressive behaviour
• CDH13 – linked to substance abuse and ADHD
• Individuals with this combination 13 times more likely to have a history of violent behaviour

Question 4

Outline the diathesis-stress model of crime

Answer 4

The tendency for criminal behaviour may be established genetically, but it is likely that an environmental ‘trigger’, such as a traumatic or dysfunctional childhood, is needed to cause the criminal behaviour. This is known as the diathesis-stress model.

Question 5

Evaluate genetic explanation of crime - Dutch family

Answer 5

Brunner (1993) – studied 28 male members of Dutch family with history of impulsive and violent criminal behaviour, members of this family were likely to have deficiency of MAOA gene – supports idea of candidate genes

Question 6

Evaluate genetic explanation for crime - adoption studies

Answer 6

Mednick found that, of 13,000 Danish adoptees, 13.5% of those who did not have a biological parent with a criminal conviction had convictions themselves.
Of those who had one biological parent with a criminal conviction, 20% had a conviction themselves.
Of those who had two parents with a criminal conviction, 24.5% had a conviction themselves.
This supports that there may be a genetic basis for criminal behaviour, which is moderated by the environment (supporting diathesis-stress).

However, there are problems with adoptees studies, as late adoption means that biological parents influence may be difficult to measure, particularly if they still see their parents.