⭐️ genetic factors of aggression✅ Flashcards
twin studies:
what have several twin studies shown?
who looked into MZ and DZ twins?
what did they find?
heritability accounts for 50% of the variance in aggressive behaviour
coccaro studied monozygotic and dizygotic male twins.
he expected to fund higher levels of aggression in MZ twins because they share 100% of the same genetics if genetics is a cause of aggression.
concordance rates of 50% for MZ twins and 19% for DZ’s
adoption studies:
what do adoption studies suggest about genetics?
what do adoption studies suggest about environmental factors?
similarities of aggressive behave. between an adopted child and their biological parent suggest genetic factors are operating
there are similarities of aggression between adopted children and their adoptive parents
adoption studies:
what did Rhee and Waldman carry out?
what did they find?
a meta- analysis of adoption studies of direct aggression and antisocial behave.
genetic influences accounted for 41% of the variance in aggression.
the MAOA gene:
what does MAOA regulate?
what variant of the gene is linked to high levels of aggression?
serotonin
the MAOA-L variant (MAOA-low) = low activity, low serotonin
the MAOA gene:
what is this gene nicknamed as and why?
how did brunner et al further cemment this notion?
what did he find abut this men?
‘warrior gene’ - it was passed by many Maori men who are known for being ferocious warriors.
studied men from a large dutch family who were repeatedly involved in impulsively aggressive violent crimes such as rape.
they had abnormally low levels of the enzyme MAOA as well as the MAOA-L variant
this means less serotonin. is broken down int the synaptic cleft so less goes into the post synaptic neutron, making it. more likely for them to be aggressive
gene- environment interaction:
- what must the MAOA-L gene be linked to in order to relate to aggression?
- what did frazetto find?
- what did those men with he MAOA-L variant that had no childhood trauma show?
- what is this an example of?
- traumatic early life experiences.
- an association between higher levels of aggression and the MAOA-L variant in men but only those who had experienced significant trauma as a child.
- they showed how lives of aggression
- diathesis stress
AO3:
✅ 2 strength?
❌ 2 weaknesses?
✅ theres research to support - BRUNNER studied men from a large dutch family who were repeatedly involved in impulsively aggressive violent crimes such as rape. they had abnormally low levels of the enzyme MAOA as well as the MAOA-L variant. this means less serotonin. is broken down int the synaptic cleft so less goes into the post synaptic neutron, making it more likely for them to be aggressive ….. supporting the genetic explanation
✅ research to support mednick and Hutchings… looked at danish adoptees found around 10% w NON CRIMINAL BIOLOGVCAL DADS became criminal compared to around 21% w CRIMINAL BIOLOGICAL DADS became criminal… swot g criminality ca be genetically inherited
❌ the precise mechanism of the the MAOA - serotonin aggression link is unclear .
❌ twin studies may lack validity - equal environment assumption, twin m ay grow up in different environments … biologically determined, doesnt consider other factors
mednick and Hutchings
who did they study?
what % had a biological NON - criminal dad became criminal?
what % that had a biological criminal dad and became criminal?
what does this show?
- danish adoptees
- around 10%
- around 21%
- shows that criminality can be genetically inherited
