genetic factors aggression

Question 1

twin studies

Answer 1

• mz twins = have 100%
• dz = share 50%

mz twins = more alike in terms of aggressive behaviour

adult twins = 50% of the variance in aggression towards others = due to genetics

Question 2

adoption studies.

Answer 2

• adoptees aggressive behaviour correlates more with the biological parents than the adoptive parents = genetic influence applied
• hitching and mednick = study on 14000 adoptees in Denmark, found significant number of adopted boys with criminal conviction had violent criminal convicted biological parents , provides evidence for genetic link

Question 3

maoa

Answer 3

• no specific gene that correlates with aggression ,but maoa has links to it
• maoa = regulates serotonin
• low levels of serotonin = high lvls of aggression

brunner et al - study on dutch family with history of aggression , found the they all had aborally low levels of maoa and a defect of the gene

Question 3

maoa L

Answer 3

• this variant (warrior gene), associated with low levels of maoa
• occurs in 2/3 of people in populations with history of warfare
• ppl with maoa H = less indirect aggression compared to those with the L gene
• capsi, study on 500 boys, found that those with maoa L gene were more likely to behave anti socially as adults , only after childhood maltreatment

Question 4

ao3 neg

Answer 4

p - hard to establish genetic contribution to aggression

e - e.g more than one gene usually contributes , and there’s many environmental influences on aggressive behaviour

e- genetic and environmental factors may interact with each other

l- connection between genetic and enviro factors, far from straght it forward

Answer 5

p- most studies focused on ppl convicted of violent crimes

e- but convicted crims only are only a small amount of people who actually commit crimes

e- + ppl seen as violent based on a court conviction aren’t really the most persistent or serious offenders

l- may ex

Question 6

ao3 tilhonen

Answer 6

p - role of maoa gene in violent behaviour = supported by reaseac

e- tilhonen, found very violent behaviour in Finnish prisoners = associated with L gene in combo with cdh13 gene

e- not substantial evidence in this gene in non violent offenders, shows that this genetic combo is specific to violent behaviours only

Question 7

ao3 gender

Answer 7

p - gender diff in aggression = explained by maoa gene

e- e.g maoa = linked to x chrom, men have 1, woman have 2

e- for woman , undamaged second X chromosome with normal maoa gene may prevent expression of the abnormal version of it

l- explains why males = more aggressive than females