Genetic Explanations

• What do genetic explanations suggest?

  Aggressive behaviours are inherited
• Twin studies

  Aggression =innate we should see increased aggression in MZ than DZ

  
  

  AO3-

  Coccaro - compared MZ and DZ male Vietnamese

  • Concordance rate for MZ of 50% and DZ of 19% in terms of physical acts of aggression
• Adoption studies

  + correlation between adopted children and biological parents = genetic - nature

  + correlation between adopted children and adopted parents = environment - nurture

  
  

  AO3-

  Mednick and Hutchings - studied Danish adopted children

  • 21.4% of adoptees with criminal biological fathers were criminal
  • 10.5% of adoptees with non criminal biological fathers were criminal
• Gene candidates for aggression are genetic codes (genotype) that are associated with display of aggressive behaviour (phenotype)
• XYY - early research

  ---> only affects males. Everyone born with X & Y chromosome

  Additional Y - referred to as supermales = taller, more aggressive, lower levels of empathy
• MAOA gene

  ---> enzyme that breakdown serotonin. Low levels of MAOA-L is linked to aggression

  Low production = higher levels of serotonin in brain

  Low activity variant (warrior gene) is found in 1/3 of western men
• Strength of genetic explanations

  Empirical support

  Provides evidence that aggression has genetic component

  Brunner et al - case study on Netherlands family.

  • Males that had history of impulsive aggression & attempted rape had low MAOA activity

  Supports MAOA and aggression can be linked to aggression

  + Any of the twin or adoption study
• Limitation of genetic explanations

  Low generalisability

  
  

  Many studies e.g. Brunner et al rely on small samples. This is an issue because it means that findings cannot represent a range of different people

  
  

  Limits internal validity of explanation as a whole
• Strength of genetic explanations

  Real world application

  Understanding genes formed interventions

  • e.g. early identifications for at risk individuals can be given targeted therapy, genetic screenings and medication

  Increasing validity
• Limitation of genetic explanations

  Biologically reductionist

  Oversimplifies aggression. Focuses too narrowly on biology

  Ignoring crucial factors e.g. upbringing or environment - SLT
• Limitation of genetic explanations

  Difficult to explain

  Researchers may not be able to differentiate if its multiple genes or 1 singular gene (e.g. MAOA) leading to aggression

  Decreases reliability - findings may not be as objective as we think