AC2.1 Biological Theories of criminality

• What is the nature vs nurture argument?


  The debate on whether of genetics can determine our behaviour (nature) or if it is our environment, upbringing and life experiences that have ‘nurtured’ us into behaving in certain ways
• What are the Biological theories of criminality

  • Lombroso
  • Sheldon
  • XYY Theory
  • Adoption
  • Twin studies
• What is the XYY Theory?

  • Males that are born with an extra Y chromosone
  • These men are know as super males
  • They are more aggressive and violent than single Y chromosome men, have higher levels of testosterone, muscular and tall with a low IQ
• What is evidence for the XYY male theory?

  • Jacob eat al (1995) found that XYY men are over represented in prison
  • 15 in 1000 men have the condition in prison- compared to 1 in 1000 in general population
  • This shows that your biology plays a part in your criminality
• What case study is there for an XYY male?

  • John Wayne Gacy
  • has 33 victim (known), never expressed remorse, killed, tortured and abused boys as young as 14 years old and older men
  • He had a traumatic childhood as a result of an alcoholic father who physically and psychologically abused Gacy with homophobic taunts
• What are the evaluation of the XYY theory?


  Weakness:

  • XYY syndrome is rare, occurring in 1 in 1000 males. While around 80% of crime is committed by males
  • Difficult to separate upbringing from genetic factors

  Strengths:

  • Price and Whitmore found that XYY males were unstable, and likely to commit motiveless crimes
• What are the 2 types of twins?

  • Dizygotic (non identical)= Born at the same time but come from 2 separate eggs and share 50% of the DNA
  • Monozygotic twins (identical)= Born at the Same time but come from 1 egg and share 100% of the DNA
• What are concordance rates?

  the probability (as a percentage) that if one twin has a characteristic the other twin will have the characteristics e.g. the probability that if one twin is criminal, the other twin will also commit a crime
• Describe Lange’s case study for twin studies (1929)?

  • Investigated 13 MZ twins and 17 DZ twins
  • Found that 10 out of the 13 MZ twins had both served time in prison
  • Only 2 out of the 17 DZ twins had both served time in prison
  • This suggests our genes influence us to commit crime

  HOWEVER… he should have done a larger sample to have better results
• Describe Christiansen’s 1977 study

  He investigated 3586 twin pairs born in Denmark and looked at the concordance rate for criminality

  results :

  • Males, 35% MZ, 13% DZ
  • Females 21% MZ, 8% DZ
• What is the adoption study of criminality?


  Adopted children are compared to their biological and adoptive parents to see which has more influence- biology or environment
• What is the case study to support Adoption study?

  • Mednick et al (1975)
  • Studied 14,000 adopted boys and found high proportion of boys with criminal conviction had biological parents with criminal convictions
  • This suggests that there is a strong link between genetics and criminality
  • If the biological parents, but not the adoptive parents, qualify as criminal, 20% of their sons turn out to be criminal
• What is Lombroso’s theory of criminality?

  • He suggested that criminals were a species that failed to evolve at the same pace
  • Said they were ‘throwback”: Their ‘atavistic’ (primitive features) were biological characteristics from an earlier stage of human developments which indicated biological inferiority
• What method did Lombroso use to carry out his research?


  Examined the features and measurements of nearly 4,000 criminals, skulls of 400 dead criminals

  Results: sloping brow ( he said this indicated low intelligence), pronounced jaw, high cheekbones, large ears, extra nipples, toes and fingers
• Evaluate Lombroso’s theory

  • He did not use a control group in his research
  • Goring 2013 tried to replicate his findings by comparing a large group of offenders with a control group of non offenders and found non significant differences between the 2 groups
  • Scientific racism, these were mostly specific to people of African decent (DeLisI)
• What is Sheldon’s somatotype theory?


  He suggested that our body types can be linked to our personality and temperaments and therefore is a cause of criminality
• What are the 3 body types Sheldon identifies?

  • Endomorph: fat and soft, tend to be sociable and relaxed
  • Ectomorph: thin and fragile, are introverted and restrained
  • Mesomorphic: hard and muscular, tend to be aggressive and adventurous
• What body type did Sheldon identify to be most likely criminal and least likely?

  Using a correlation study he found that most offenders were mesomorphic and they were least likely to be ectomorphs
• How does brain abnormalities link to criminality?

  Damages or changes in the brain can affect a person’s behaviour
• Case studies used for brain abnormalities


  • Charles Whitman
  • Phineas Gage
• Charles Whitman

  Killed 16, injured 31 people. He had a brain tumour pressing on his amygdala, which is a region in the brain that controls our behaviour and our emotions. This suggests that there is a link between the brain and criminal behaviour.
• Phineas Gage

  Tried to level land with dynamite. Had a 3 foot inch rod projected into his brain. It entered via his cheek, left eye and into his frontal lobe. The rod damaged the prefrontal cortex. It didn't affect his memory or movement of speech, but his behaviour changed within months. He became extravagant, anti-social, foul-mouthed with bad manners, frequently got into fights.
• What evidence is used to prove brain abnormalities?

  Raine et al (1994) used 3D scans of killers’ brains. It found that criminals were more likely to have damage to the prefrontal cortex, which is linked to our personality and control
• What are neurotransmitters?


  Chemical messengers that transmit signals between neuron's in the brain and nervous system.

  One of these is serotonin, which is a natural chemical in your brain that controls whether or not you are happy, regulating mood and behaviour
• Describe Scerbo and Raine’s study on neurotransmitters


  They conducted a meta-analysis of 29 studies into antisocial adults and children and found low. levels of serotonin associated with all of them.

  The idea is that low levels of serotonin is associated with higher levels of aggression (and therefore violent crime)