Genetics

• The genetic explanation for offending suggests that offending behaviour is inherited as one of more genes predispose people to commit crime. There are three topics within genetic explanations:

  • twin studies
  • candidate genes
  • diathesis stress model
• Genetic Explanations: Twin Studies

  There are two researchers who investigated twin studies as a genetic explanation for behaviour; Lange and Christiansen
• Genetic Explanations: Twin Studies - Lange

  In 1930, Lange looked at 13 MZ twins and 17 DZ twins where one of each pair had served time in prison. 10 of the MZ twins and 2 of the DZ twins had both been in prison. From this he concluded that genetic factors play a predominant part in offending.
• Genetic Explanations: Twin Studies - Christiansen

  In 1977, Christiansen studied 87 MZ twins and 147 DZ twins and found a concordance rate (they had both been in prison) of 33% for MZ twins and 12% for DZ twins. This supports the theory that genetics have an offending component.
• Genetic Explanations: Candidate Genes

  In 2014, Tiihonen conducted a genetic analysis on 900 Finnish offenders and found 2 abnormalities on 2 genes which may be associated with violent crime:

  • MAOA: controls dopamine and serotonin, has been linked to offending behaviour
  • CDH13: linked to substance abuse and ADD

  In this sample, individuals with this high risk combination were 13 times more likely to have a history of violent behaviour. However this research is in its early stage and hasn't been replicated.
• Genetic Explanations: Diathesis Stress Model

  Diathesis stands for genetic predisposition and stress means environmental trigger. If genetics do influence offending, it will likely be partly influenced by the environment. A tendency towards criminal behaviour is likely to come out via a combination of genetic predisposition and environmental triggers, such as criminal role models and a dysfunctional environment.
• What is the role of the MAOA gene?


  Controls serotonin and dopamine,