Aggression- genetic explanations Flashcards
Why are twin studies used when investigating genetic explanations?
MZ twins share 100% of their DNA and they not only provide a control sample for each other but can be compared to DZ twins
What do twin studies conclude?
-If MZ twins are more similar in terms of aggressive behaviour it should be down to genes rather than the environment as they both share the same environment
Why are adoption studies used?
-Highlight differences between biological and adoptive parents and their children
-Assess to what extent the environment and genetics influence behaviour
What did Foccrara et al find in his study on MZ and DZ twins?
-For aggressive behaviour (physical assault) concordance rates of 50% for MZ twins and 19% for DZ twins)
-For verbal aggression the rates were 28% for MZ and 7% for DZ twins
What was the procedure for Rhee and Waldmans study?
-Meta analysis study of 52 twin and adoption studies
What did Rhee and Waldmans study conclude?
Environmental factors can only be an explanation for aggression if the specific genetic factors are already present
What does the MAOA gene stand for?
monoamine oxidase gene
What is the role of the MAOA gene?
Regulates key neurotransmitters, particularly serotonin
Does the low activity form produce more or less of the enzyme?
Less
What does a dysfunctional MAOA gene lead to?
An imbalance of serotonin and, possibly, to an increase in aggression
What was the procedure of Brunner et al study?
-Study of 8 men from a Dutch family
-studied them because they showed high levels of impulsive aggression
-Assessed them using IQ tests + physical examination
-Interviewed the family members about their behavioural characteristics history
What were the results of Brunner’s study?
-Abnormally low levels of MAOA gene which was later found to be defected
-Displayed aggressive and criminal behaviour
-Positive correlation between defected MAOA gene and aggressive behaviour
Give a positive of Brunner’s study
High validity-multiple types of data involved
Give 3 limitations of Brunner’s study
-Correlation does not mean causation
-Poor population validity
-IQ (intelligence) does not ink to aggression
What did research such as Frazzeto et als study conclude?
A faulty MAOA gene alone is not enough to produce aggressive behaviour, rather it is the combination of a traumatic childhood with the faulty gene that is responsible for extreme aggression