Genetic Factors

Question 1

Coccaro (1997)

Answer 1

50% concordance rate for specifically aggressive behaviour (physical assault) in MZ twins, 19% DZ

Question 2

Rhee & Walkman (2002)

Answer 2

Meta-analysis of adoption studies of direct aggression and antisocial behaviour found genetic influences accounted for 41% of variance in aggression

Question 3

MAOA gene

Answer 3

Controls production of MAO-A enzyme which metabolises monoamines (eg. Serotonin). Low levels of serotonin are associated with high levels of aggression. The MAOA-L allele results in low activity MAO-A enzyme which is associated with aggression

Question 4

Strengths of genetic factors

Answer 4

• Research supporting role of genetics (eg. Rhee & Walkman meta-analysis found genetic influences accounted for 41% of variance in aggression)
• Research supporting MAOA gene (eg. Godar found removal of MAOA gene in mice lead to increased aggression and serotonin)

Question 5

Limitations of genetic factors

Answer 5

• Difficulty measuring genetics alone (eg. McDermott showed p’s with MAOA-L acted aggressively in money allocation experiment but only when provoked, otherwise acting same as MAOA-H, suggesting interactionist approach)
• Difficulty determine role of specific genes (eg. Stuart showed intimate partner violence in men not just associated with MAOA-L but also 5-HTT)