aggression - genetic factors

Question 1

twin studies and aggressive behaviour

Answer 1

there is a heredity between 50% of the variance in aggressive behaviour.

Question 2

coccaro et al 1997

Answer 2

studied men who were either monozygotic and dizygotic twins

Question 3

what were the findings of coccaro’s study?

Answer 3

physical violence:
- mz = 50% concordance rate
- dz = 19% concordance rate
verbal aggression:
- mz = 28% concordance rate
-dz = 7% concordance rate

Question 4

adoption studies and aggression

Answer 4

adopted children and their bio parents = genetic influence.
adopted children and their adoptive parents = environmental influence.

Question 5

meta-analysis - adoption studies

Answer 5

compared levels of anti-social behaviour showed that there was a genetic influence of 41% in aggression - similar to twin studies.

Question 6

what is the MAOA gene?

Answer 6

this controls the production of an enzyme called monoamine oxidase A, the role of it is to breakdown serotonin after a nerve impulse has been transmitted.

Question 7

what is MAOA-L?

Answer 7

low activity variant has been linked with high levels of aggressive behaviour, this means less serotonin is broken down which leads to high levels of serotonin in the synapse.

Question 8

research support for the MAOA gene:

Answer 8

brunner et al 1993 found that 28 men from a dutch family were involved in impulsively aggressive behaviour, it was found that there were lower levels of the enzyme MAO-A and MAOA-L,

Question 9

genetic-environment interaction

Answer 9

despite genes being crucial in influencing aggressive, they do do not function in isolation. MAOA-L gene is only associated with adult aggression when paired with early traumatic life experiences.

Question 10

frazzetto et al 2007

Answer 10

associated between high levels of anti-social aggression and MAOA-L gene in men, they had experienced significant trauma for the first 15 year of their life