Outline two biological explanations for offending (6 marks) - Genetic

Twin and adoption studies suggesting that genes predispose offenders to crime pt 1

Christiansen (1977) studied over 3500 twin pairs in Denmark finding a concordance for offender behaviour of 35% for MZ males and 13% for DZ. males (slightly lower rates for females) This supports a genetic component in offending.

Twin and adoption studies suggesting that genes predispose offenders to crime Pt 2

Crowe (1972) found that adopted children who had a biolgocial mother with a criminal record had a 50% risk of having a criminal record at 18. Whereas adopted children whose mother didn’t have a criminal record only had a 5% risk.

Candidate genes

A genetic analysis of about 800 offenders by Tihonen et al (2015) suggested two genes that may be associated with violent crime:

• MAOA gene regulates serotonin and linked to aggressive behaviour

• CDH13 gene linked to substance abuse and ADHD

• The study found that 5-10% of all severe violent crime in Finland is attributed to the MAOA and CDH13 genotypes

Distress stress model

If genes have an influence on offending, this influence is likely to be at least partly moderated by environmental factors.

The diathesis-stress model suggests that a tendency to offending behaviour is due to a combination of

• Genetic predisposition (diathesis)

• A biological or psychological stressor or ‘trigger’ (e.g criminal role models or dysfunctional upbringing)