Genetic factors in aggression Flashcards
(8 cards)
How have twin studies shown the genetic element to aggression?
MZ twins vs DZ twins - found using adult twin pairs that nearly 50% of the variance in direct aggressive behaviour could be attributed to genetic factors (Coccaro et al)
How have adoption studies show the genetic element to aggression?
Hutchings and Mednick - study of over 14000adoptions in Denmark found that a significant number of adopted boys with criminal convictions had biological parents with convictions for criminal violence, providing evidence for a genetic effect
What research is there on genetic factors in aggression?
Miles & Carey carried out a meta-analysis of 24 twin + adoption studies that demonstrated the genetic basis for aggression (strong genetic influence that could account for 50% of the variance in aggression)
Age important - genes/family environment influential in youth
What is the role of the MAOA gene for aggression?
Associated with aggressive behaviour - regulates metabolism of serotonin in the brain + low levels of serotonin are associated with impulsive and aggressive behaviour
Brunner - Dutch family with many males who were involved in violent crimes had abnormally low levels of MAOA + defect later identified
What is the MAOA-H gene and MAOA-L gene?
Caspi et al - study of 500 children - discovered a variant in gene
MAOA-L were significantly more likely to grow up to exhibit anti-social behaviour but only if they had been maltreated as a child
Those with the MAOA-H who were maltreated and those with MAOA-L who were not maltreated did not display anti-social behaviour
Why is MAOA-L commonly known as the ‘warrior gene’?
More frequent in populations with a history of warfare, with about 2/3s of people in these populations having this gene
What difficulties are there with determining the role of genetic factors?
More than one gene usually contributes to a given behaviour
Non-genetic influences on the manifestation of aggressive behaviours
Genetic factors and environment may interact with one another
Difficult to identify the specific contribution of genetic factors to aggressive behaviours
What are the problems with assessing aggression?
Miles and Carey meta-analysis - mode of assessment was found to be a significant factor
Self-report/parental studies show genetics as being more important but observational techniques suggested that genetics made less of a contribution and environmental factors had a greater influence
These inconsistencies make it hard to accurately assess the relative contributions of genetic and environmental factors in aggression
