- Twin studies
- Importance of genes is illustrated by twin studies
- 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
- Genetic factors must play an important part
- Candidate Genes
- Jari Tiihonen et al (2014)
- 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
- Jari Tiihonen et al (2014)
- Diathesis-Stress Model
- Genetic influence may be moderated by environmental influence
- Criminality may come about through genetic predisposition as well as biological or psychological trigger