genetic factors Flashcards
(5 cards)
what types of studies show a genetic basis to aggression
- twin studies (concordance rates)
coccaro et al.
physical aggression = 50% in MZ, 19% for DZ
verbal aggression = 28% in MZ, 7% for DZ - rhee and waldman
= adoption meta-analysis looking at direct aggression and antisocial behaviour
- found genetic influence accounted for 41% of variance in aggression
link between MAOA ‘warrior’ gene and aggression
MAOA gene = regulate production of enzyme MAO-A, which is involved in breakdown of serotonin
- low activity variant of MAOA (MAOA-L) = reduced production of MAO-A = serotonin imbalance = linked to higher aggression levels
lea and chambers = 57% of maori men, vs 34% of caucasion males had MAOA-L
maori people = historically associated for being fierce warriors (hence ‘warrior gene’)
weakness of genetic basis for aggression (gene-environment interactions)
genes = do not function in isolation = reductionist explanation
frazzeto et al = association between low activity MAOA and higher levels of antisocial aggression only found in males who has experienced significant trauma in first 15 yrs of life
- no trauma = not particularly high adult aggression even if possessed low activity MAOA
= diathesis stress model
strength of genetic basis to aggression
research support
= for role of MAOA in aggression
mertins et al = money distributing game using low activity and high activity MAOA variant male pps
= men with high activity variant more cooperative + made fewer aggressive moves than low activity pps
= support relationship between MAOA activity and aggression
further weakness of genetic basis to aggression
twin study problems
= lack validity
equal environment assumption = DZ twins share environment to same extent as MZ twins
- not the case, MZ twins tend to be treated more similarly than DZ
= concordance rates from twin studies may be inflated = genetic influence overexaggerated
