, biological theory

• Monozygotic twins


  Identical twins, they share 100% of their DNA and develop from the same fertilized egg
• Dizygotic twins


  Non-identical twins, they don't share 100% of their DNA
• Concordance rate


  The percentage of cases where if one twin has a criminal conviction, the other twin also has a criminal conviction
• Christensen's twin study found a 52% concordance rate between monozygotic twins
• Christensen's twin study found a 22% concordance rate between dizygotic twins
• High concordance rate between monozygotic twins


  Suggests criminality is genetic
• Low concordance rate between dizygotic twins

  Suggests criminality is genetic
• Adoption studies


  Compare the behaviour of adopted children to their adopted parents and their biological parents to test if criminality is environmental or genetic
• Mednick's adoption study found adopted sons were more likely to have a criminal record if their birth parent had a criminal record, but less likely if their adoptive parent had a criminal record
• Mednick's adoption study provides support for genetic theories of criminality
• Somatotypes


  Body types identified by Sheldon
• Somatotypes identified by Sheldon

  • Ectomorph
  • Mesomorph
  • Endomorph
• Ectomorph


  • Thin and fragile, lack fat and muscle, flat chested, narrow hips and shoulders, thin faces
  • Personality: self-conscious, fragile, introverted, emotionally restrained, thoughtful
• Endomorph


  • Rounded and soft, lack muscle tone, wider hips
  • Personality: sociable, relaxed, comfortable and outgoing in social situations
• Mesomorph


  • Muscular and hard-bodied, little fat, strong limbs, broad shoulders and narrow waists
  • Personality: adventurous, sensation-seeking, assertive, domineering, enjoy physical activity
• Sheldon argued that mesomorphs are the body type most likely to engage in criminal behaviour
• Sheldon suggested mesomorphs are more likely to be attracted to the risk-taking involved in crime, and their imposing physique and assertiveness can be important assets in crime
• Two weaknesses with Sheldon's theory could be suggested
• Atavistic


  Throwbacks to an earlier primitive stage of evolution
• Criminals (according to Lombroso)


  • Pre-social
  • Unable to control their impulses
  • Reduced sensitivity to pain
• Physiological features of criminals (according to Lombroso)


  • Large protruding ears
  • Sloping forehead
  • Large jaw
  • Prominent eyebrow arches
  • Large eye sockets
  • High cheekbones
  • Beak-like noses (for murderers)
  • Flatter noses (for thieves)
• Lombroso saw criminals as like savages or even apes, and that in a more primitive society they would have been normal but in modern society they were abnormal
• Lombroso's theory is very much an 'us and them' theory, with criminals versus normal people
• Lombroso's research methods


  1. Measuring the facial features and heads of thousands of prisoners

  2. Recording these measurements
• Lombroso claimed that criminals could be identified by their distinctive physical features
• Lombroso argued that criminals were physically different from non-criminals
• Lombroso put his theory forward in 1876
• Lombroso was one of the first physiological theorists of criminality