Genetics:

• AO3: TWINS AND GENES

  LIMITATION:

  • use of twin studies is the assumption of equal environments
  • it is assumed by researchers studying twins that environmental factors are held constant because twins are brought up together therefore must share similar environments
  • However, this shared environment assumption may apply much more to MZ twins as they look identical and people (especially parents) tend to treat them similarly than DZ twins which in turns affects their bevhaviour.
  • Therefore higher concordance rates for MZ in twin studies may simply be because they are treated similar than DZ twins
• AO3: TWINS AND GENES

  STRENGTH:

  • Support for the diathesis stress model
  • Mendick et al 1984 studied 13,000 Danish offenders
  • When neither the biological or adoptive parents had a conviction the % of adoptees that did was 13.5
  • This rose to 20% when either the biological or adaptive parents had one
  • Further increased to 24.5% if both did
  • This shows that genetic inheritance plays an important role in offending behaviour but environmental factors are clearly important, providing support for the diathesis model of crime