Lange and Christiansen

• Claims

  • genetic theory, Twin Studies Theory
  • monozygotic twins will either both be criminal or neither will
  • criminality is a result of your genetics
• Components

  • Lange: studied 30 sets of twins, 10/13 MZ twins had both been to prison, 2/17 DZ twins had both been in prison
  • Christiansen: studied 3586 sets of twins, concordance rates of 35% in male MZ twins and 13% in male DZ twins, concordance rates of 21% in female MZ twins and 8% in female DZ twins
  • has to be genetic as concordance rates for MZ twins were higher
• Credibility

  • links genetics to criminality
  • can be repeated
  • scientific experiment with results that proved their theory
  • no genetic testing
  • reductionist
  • deterministic
• Application

  • the Kray Twins: MZ twins who created a criminal empire and were involved in a variety of violent crimes
• Refuting Evidence

  • fairly low concordance rates
  • no genetic testing to verify if the twins were monozygotic or dizygotic
  • not carried out over a long enough period
• Support Evidence

  • Lange and Christiansen came to the same conclusion
  • Bouchard 1979: studied MZ twins separated at birth who had different upbringings, found they had similar attitudes and personalities