GENETIC INFLUENCES

• GENETIC INFLUENCE?

  MAOA gene
• MAOA GENE?

  • produces enzyme associated with aggressive behaviour
• MAOA EVALUATION?

  + Brunner et al

  + Caspi et al

  + Mcdermott et al

  -sampling

  -role of genetic factors

  -assessing aggression

  + Tiihonen et al

  + explains gender differences
• BRUNNER ET AL?

  • 1980s
  • Dutch males in family
  • violent crimes
  • low levels of MAOA
  • gene defect
• CASPI ET AL?

  • 500 male children
  • MAOA-H variant (high MAOA) and MAOA-L variant (low MAOA)
  • MAOA-L variant and mistreated leads to antisocial behaviour
• MCDERMOTT ET AL?

  • warrior gene (MAOA-L)
  • higher in populations with history of warfare
  • MAOA-L had higher aggression when provoked than MAOA-H
• SAMPLING?

  • unrepresentative
  • restricted sample
  • violent criminals
• ROLE OF GENETIC FACTORS?

  • multiple genes
  • non-genetic factors
• ASSESSING AGGRESSION?

  • parental/ self-reports not reliable
• TIIHONEN ET AL?

  • Finnish prisoners
  • MAOA-L and CDH13 predicted aggression
• EXPLAINS GENDER DIFFERENCES?

  • linked to X chromosomes
  • higher instances in males
• MAOA PROTEIN/ ENZYME?

  • metabolises noradrenaline, serotonin and dopamine
  • dysfunctional gene means they are not broken down as not enough MAOA produced
  • too much adrenaline causes...
  • hypersensitivity in fight or flight
  • overreactions to external stimuli
  • perceive non-existent threats
  • too much dopamine causes increased likelihood of feels of reward when aggression carried out
  • too low serotonin causes a lack of inhibition over impulsive behaviour