Genetic Factors AO1 & AO3 Flashcards
How is the heritability of aggression studied?
AO1
Through Twin Studies;
MZ twins share 100% of DNA
DZ twins share 50% of DNA
What concordance rates were found in physical and verbal aggression in twins?
Physical - MZ = 50% DZ = 19%
Verbal - MZ = 28% DZ = 7%
what do adoption studies show about aggression?
that environmental influences are operating
who carried out a meta-analysis on adoption studies?
Rhee and Waldman
On direct aggression and antisocial behaviour
what did Rhee and Waldman find?
that genetic influences accounted for 41% of the variance in aggression
what gene is responsible for ‘mopping up’ neurotransmitters in the brain?
the MAOA Gene
aka Monoamine Oxide
what can a faulty MAOA gene cause?
can lead to abnormal activity of the MAOA enzyme thus affecting levels of serotonin
What did Brunner study?
28 males in a Dutch family who were repeatedly involved in impulsively aggressive crimes.
they found that they had abnormally low levels of MAOA in their brains and its low-activity varient.
What is low MAOA gene activity related to?
adult aggression combined with early traumatic life events
what did Frazzetto find an association between?
high levels of antisocial aggression and low activity MAOA gene variant.
BUT only when the ppts had dealt with significant childhood trauma
What is the relation between the MAOA gene and trauma in causing aggression called?
Gene-Environment Interactions
GxE
why is it hard to see how influential genes are on aggression?
AO3
it is hard to separate genetic and environmental factors as a person can possess a gene associated with aggression but it is only expressed if the environment is favourable.
What did Vassos find in their meta-analysis?
What does this say about the genetic influences on Aggression?
AO3
they found no evidence of an association between and single gene and aggression. they claim it is because even several genes are unlikely to fully explain behaviour as multifaceted as aggression.
It shows that their are multiple genetic influences, not just one
Why is it difficult to draw valid conclusions about the role of genetic factors?
AO3
methods of measuring aggression differ between studies.
Rhee and Waldman found in their meta-analysis that genetic factors had a greater influence on aggression in studies that used self-report rather than parent/teacher reports.
