Genetic Factors In Aggression Flashcards
What do twin studies show
Genetic factors account for about 42% of variance in aggressive behaviour
What did Coccaro et al study
Adult male MZ and DZ twins for direct physical aggression
What did Coccaro et al find
Concordance rates of 50% in MZ twins and 19% in DZ twins
What were the results for verbal aggression
28% for MZ twins and 7% for DZ twins
What did adoption studies show
Genetic factors account for about 41% of variance in aggressive behaviour
What suggests that there are genetic influences operating
Similarities in aggressive behaviour between an adopted child and biological parents
What did Rhee and Waldman do
Meta-analysed adoption studies and found genetic influences accounted for 41% of the variance in aggression
What is linked to low serotonin
MAOA
What is MAOA
An enzyme that mops up neurotransmitters after a nerve implied has been transmitted between neurons
What does MAOA do
It breaks down the neurotransmitter into constituent chemicals to be recite cold or excreted
What is determined by a MAOA drug?
The production of the enzyme
What may a dysfunction in the operation of this gene lead to
Abnormal activity of the MAOA enzyme which affects levels of serotonin
Name one variant of the MAOA gene
The warrior gene
What is the warrior gene
A variant of the MAOA gene that leads to low MAOA activity in the brain and is associated with aggressive behaviour
What did Brunner et al study
28 male members of a Dutch family repeatedly involved in impulsively aggressive violent criminal behaviours (e.g. rape, attempted murder)
What did Brunner find
These men have both abnormally low levels of MAOA in the brains and the low activity version of the MAOA gene
What did the most violent domestic abusers have
Low activity MAOA gene
What did Stuart et al study?
97 man from a treatment program for domestic abuse who had inflicted a form of aggression called intimate partner violence
What did Stuart et al find
Man with the low activity MAOA gene one the most violent perpetrators of IPV
What did Fraxxetto et al find
An association between antisocial aggression and the low activity MAOA gene variant in adult males but only in those who experienced significant trauma during the first 15 years of life
What was found about those who had not experienced trauma
They were not especially aggressive as adults even if they possessed the gene variant
What can be concluded from Frazzetto et al’s findings
These findings together are strong evidence of a gene environment interaction (sometimes called diatheses stress)
Name a disadvantage of genetic factors of aggression
Difficult to isolate - it’s difficult to separate genetic and environmental factors - someone with an aggression associated gene they only behave aggressively if the environmental conditions are suitable - proven to be challenging to establish exactly how influential genes are in aggressive behaviour
