Genetic Factors in Aggression

Question 1

what is the genetic factor in aggression

Answer 1

MAOA gene

Question 2

outline genetic factors in aggression
- genetics

Answer 2

if aggressive behaviour is genetic, it must therefore be inherited through family lines.

psychologists have investigated this by using family, twin and adoption studies.

twin studies involve comparing identical (monozygotic) and non-identical (dizygotic) twins where one twin shows particularly aggressive behaviour to see how often the other twin also shows aggressive behaviour to establish a concordance rate.

if aggression is genetic, concordance rates would be expected to be significantly higher in MZ than DZ twins.

Question 3

outline genetic factors in aggression
- MAOA gene

Answer 3

recent research has identified a particular gene as playing a key role in aggression.

the monoamine oxidase A (MAOA) gene is responsible for producing a protein called monoamine oxidase A.

MAOA regulates the metabolism of serotonin (a neurotransmitter) in the brain.

if the MAOA gene is defective, this is though to lead to low levels of serotonin.

as serotonin has a widespread inhibitory effect on the brain, it is thought that this low serotonin makes it more difficult for the person to inhibit the emotional responses generated by the amygdala (an emotional centre in the brain) leading to an increased risk of impulsive and aggressive behaviour.

Question 4

evaluate genetic factors in aggression - MAOA gene
- STRENGTHS

Answer 4

P) support from Brunner (1993)
E) found a defective MAOA gene in a dutch family with a history of male violence (eg rape and arson)
L) defective MAOA gene seems to be associated with an increased risk of aggressive behaviour

P) support from Cases et al (1995)
E) disabled MAOA gene in mice which influenced serotonin levels and males became highly aggressive. females unaffected.
E) restoring the function of the gene returned male mice to regular state
L) MAOA gene can increase aggression when not functioning properly and inhibit aggression when functioning normally (only males)

Question 5

evaluate genetic factors in aggression - MAOA gene
- LIMITATIONS

Answer 5

P) focus on non-human animals
E) research findings can’t be effectively extrapolated to understanding human aggression
E) eg Cases et al ; human and mice function differently with genetic expression
L) MAOA gene cannot fully explain human aggression

P) alternative explanation from Capsi et al (2002)
E) study of 500 male children defective MAOA gene led to significant increase in chances of growing up to exhibit anti-social behaviour but only if they had been maltreated as children
E) defective MAOA gene = diathesis but aggression is triggered by environment factors (stress) such as maltreatment
L) interaction isn’t approach more appropriate

P) ignore evidence that aggression may be learned through the environment
E) Bandura bobo doll experiment
E) children observed and imitated aggression
L) suggests situational factors involved in aggression; genetic explanations are biologically reductionist and limited

P) biological determinism
E) argues we are programmed to be aggressive
E) we have no free will over aggressive behaviour
L) wrong for law to find people responsible for aggression if not under conscious control