biological theories

• Death penalty


  Ultimate way to deal with a person who is genetically driven to commit crime
• Death penalty abolished in the UK in 1969
• More studies show that the death penalty does not lower crime rates
• Eugenics


  Policy endorsed by the Nazi party to stop prisoners and 'undesirables' from having offspring
• Looks to prevent the birth of people with criminal genes
• Though improbable to see blanket sterilisations, courts can order sterilisation to citizens
• Neurochemicals


  Prison policies have encouraged diet change to lower aggression
• Virkkunen et al discovered that aggressive prisoners held lower serotonin levels and therefore encouraged the introduction of oily fish into the prison diet
• In the UK, it is good practice for prisons to offer balanced diets to prisoners
• XYY theory


  • 'Super male' – extra 'Y' chromosome
  • Men with XYY found to be aggressive
  • Studies estimate that there are 1 in 1000 men with XYY in society
  • Studies suggest that there are 15 in 1000 prisoners with XYY
• XYY theory


  • Strengths: 15 in 1000 prisoners is a substantial figure, providing credibility to the theory
  • Weaknesses: Genetic abnormalities are prevalent in society but don't signal aggression, Theilgaard refuted the claim that XYY genes were linked with aggression
• Adoption studies


  • Studies have compared the behaviour of offspring to their adopted parents and biological parents
  • Hutchings and Mednick found that a substantial amount of male offspring with criminal convictions had biological parents with criminal convictions
• Adoption studies


  • Strengths: Studies by Hutchings and Mednick show a link between offspring who are adopted and their biological parents, Removal from one environment gives greater facility to split genetic and environmental factors
  • Weaknesses: Data regarding the biological family may be kept confidential, Older adopted children may already be influenced by the environment of their biological parents
• Twin studies


  • Monozygotic (MZ) twins are identical and share an egg; dizygotic (DZ) twins come from different eggs
  • Lange found that a greater proportion of MZ twins were likely to demonstrate criminal behaviour
  • Christiansen found that male twins were more likely to share criminal characteristics compared to female twins
• Twin studies


  • Strengths: The biological relationships occur naturally, so these are natural experiments, Following twin studies, there have been greater strides to help deal with medical disorders
  • Weaknesses: The validity of twin studies have been questioned due to the small samples that had been used, making it unlikely to be proportionate to the public, Twins brought up together could be affected by nurture rather than nature