biological theories

• 3 genetic theories

  • jacob’s - XYY (1965)
  • lange - Twin (1929)
  • hutchings and mednick - Adoption (1994)
• Jacob’s - XYY

  • an extra Y chromosome in males - super males
  • increased aggression, leading to a higher rate of criminality
  • jacob’s did a study in a maximum security hospital for offenders and found that 9/315 patients had XYY syndrome
• strength of Jacob’s

  • strength- jacob’s found that 15/1000 prisoners had the extra Y chromosome, compared to the general population being 1/1000. This shows there is a correlation between criminality and the extra Y chromosome.
• 2 limitations of jacob’s

  • only 1/1000 males in the general population have the extra Y chromosome which makes it rare, yet crimes committed by males is not rare, highlighting how the XYY chromosome is not the main cause of crime.
  • only focuses on the genetic approach for criminality and ignores the behaviourist approach.
• Lange - Twin

  • monozygotic (MZ)- identical twins
  • dizygotic (DZ)- non identical twins
  • found that MZ twins have a higher concordance rate for criminality than DZ twins
  • study found that 10/13 MZ twins had both served time, yet only 2/17 DZ twins had both served time
• 2 strengths of Lange

  • supporting research- Christiansen found that 52% of MZ twins were concordant, but only 22% of DZ twins were concordant
  • twins are naturally occurring meaning that their behaviour can be easily studied.
• limitation of Lange

  • twins are brought up in the same environment, meaning it can be hard to distinguish whether criminality is because of nurture or genetics
• hutchings and mednick - adoption

  • compared criminals with both their biological and adoptive parents.
  • looked at the impact of nurture on children who are raised by adoptive parents
  • studied 14,000 adopted children and found that a high proportion of boys with criminal convictions had biological parents with criminal convictions too.
• strength of adoption

  • able to separate the effects of nature and nurture on a child’s criminality
• 2 weakness of adoption

  • information about biological parents is not always available, therefore cannot make a comparison for criminal behaviour
  • the adoption process is not always random, meaning that children are often placed in similar families and can be similar to their biological parents’ home.
• 2 physiological theories 


  Lombroso- atavistic features

  Sheldon - somatotypes
• lombroso- atavistic features

  • atavistic- something that is ancient and primitive
  • argued that the criminal is a separate species and is a ‘born criminal‘
  • criminals can be identified by atavistic features
  • experiment- studied facial and cranial features of 383 dead + 3839 living criminals - 40% had atavistic features