Genetic Influences

Question 1

Twin studies

Answer 1

MZ twins(100%)- aggression due to genes over environment
Adult twins 50% of variance in direct aggression due to genetics

Question 2

Adoption studies

Answer 2

Aggression in adopted and bio parents = genetics
Aggression in adopted and adopted parents = environment
Denmark - adopted boys with convictions have bio fathers with convictions

Question 3

Research on genetic factors

Answer 3

Miles and Corey - meta analysis 24 studies - genetics have strong influence account for 50% variance in aggression
Younger - environmental
Older - genetic

Question 4

MAOA

Answer 4

Regulate metabolism of serotonin
Brunner et al - Dutch family mutant gene low MAOA = violent crimes

Question 5

2 types of MAOA

Answer 5

MAOA H - children when mistreated were not anti social
MAOA L (warrior gene) - children when mistreated were anti social

Question 6

Strengths

Answer 6

+ Evidence- Finland study
MAOA + CDH13 = violence
Genes more impulsive
+ MAOA gene - gender differences
MAOA linked to X chromosome, when men inherit X chromosome are more likely to be affected = aggression

Question 7

Weaknesses

Answer 7

• problem sampling- only account for small no. of attackers - conviction could be a one time thing
• problem determining role of genetics
  • more than 1 gene
  • non genetic factors
  • genes and environment can interact