Genetic Explanations

• What is the concern regarding genetic explanations for aggression?

  They suggest some people are born criminals
• What will the second aggression video discuss?

  Theory and gene candidates for aggression
• What does a genetic explanation for aggression imply?

  Aggression is inherited
• Which type of twins share all their genes?

  Monozygotic twins
• What percentage of genes do dizygotic twins share?

  50%
• What did Coccaro’s research on Vietnamese twins find?

  Genetic difference accounted for 47% of assault difference
• What do family studies measure in aggression research?

  Concordance rate in aggression
• What does a higher concordance rate indicate?

  Closer genetic relations show similar aggression
• What is a limitation of twin studies in aggression research?

  Identical twins may be treated differently
• How do adoption studies help in aggression research?

  They separate genetic factors from environment
• What did Mednick and Hutchings find in their adoption study?

  Criminality is linked to genetics
• What percentage of adoptees with a biological criminal father had a criminal record?

  21.4%
• What happens if an adoptee's biological father is non-criminal?

  Only 10.5% had a criminal record
• How do genes influence aggression biologically?

  They code for biological processes in the body
• What is the XYY chromosomal disorder associated with?

  Height and aggression
• What did early researchers suggest about XYY males?

  They were taller and more aggressive
• What flaw was found in the research on XYY individuals?

  They are not more aggressive than others
• What is the MAOA gene associated with?

  Breakdown of serotonin in the brain
• What does the MAOA-L version produce?

  Low amounts of MAOA enzyme
• What is the nickname given to the MAOA-L gene?

  The warrior gene
• What percentage of western men have the MAOA-L gene?

  One third
• What is needed to trigger aggression in MAOA-L carriers?

  Combination of early child abuse and MAOA-L
• What does the diathesis stress model explain?

  Interaction of genetics and environment in aggression
• What are the findings from Brunner's case study on aggression?

  • Family with aggressive males studied
  • All had low activity MAOA gene
  • Suggests genetic makeup influences aggression
• What evidence did Stuart provide regarding MAOA and aggression?

  • Low activity MAOA found in aggressive men
  • Sample included 97 men
  • All convicted of intimate partner violence
• What is a major issue with the MAOA hypothesis?

  A third of men with the gene are not aggressive
• What does the complexity of serotonin levels suggest about aggression?

  Both high and low levels can be problematic
• What must be considered when studying genetic factors in aggression?

  • Interaction with environmental factors
  • No single gene causes aggression
  • Genetic predisposition varies among individuals