genetic explanations

Question 1

genetics AO1

Answer 1

Selective breeding of animals has shown incr aggression → TS clear hereditary factors in aggression.
Twin + adoption studies have shown a genetic factor in aggression in humans.
This may be bc extreme masculinity caused by being XYY. TIB men generally more aggressive, ∴ link between aggression + Y Chromosome.

BUT
ALLANSON: Follow up studies of XYY pts + found that XYY males are characterized by incr height but not characterized by aggressive behaviour

TS theory is untrue as although there may have been an original link between the two, further research suggests other wise

Question 2

twin studies into genetic influence of aggression

Answer 2

COCCARO 1997: assessed degree of genetic + environmental influences on aggression in males (182MZ + 118 DZ). Results → genes account for > 40% of individual diffs in aggression (genetics = stronger factor in physical v.s verbal aggression). 

TS genetics are a strong factor in aggression, but clearly not the not the only factor. Seems genes are more involved in physical aggression than verbal aggression, ∴ suggesting physical is more innate

ISSUES:
assume everything other than the genes are ‘equal’ between MZ + DZ. BUT evidence suggests parents, teachers + peers treat MZ more similarly than DZ. TIB MZ look same ∴ treated more similarly than DZ. ∴ we overestimate genetic factor

DZ may share > 50% of their genes. People marry tend to be similar (we are attracted to people similar to us) ∴ DZ may have > ‘random’ 50% of genes in common. Likely hood is parents share some genes, so to say 50% genes shared is not true, DZ may have a higher concordance ∴ we underestimate genetic factor

Question 3

adoption studies into genetic influence of aggression

Answer 3

HUTCHINGS: boys of violent criminal Bio Parents adopted to non-criminal parents more likely to be violent criminals, plus the more extensive criminal history of bio parents the higher risk the child will be a criminal.
TS biological factors are more influential than the environment
MAOA
?

Question 4

GENERAL GENETIC ESSAY PLAN

Answer 4

General genetic → breeding
Maybe maleness? → why?
Not the case → ALLENSON
But there is something genetic 
COCARO → YES → BUT twin study issue, hard to determine how much 
HUTCHINGS → more bio

Question 5

MAOA AO1

Answer 5

One gene responsible for aggression is MAOA.
→ carried on X Chromosome.
→ codes for an enzyme (MAO) - breaks down neurotransmitters such as serotonin or norepinephrine/noradrenaline.
→ Low activity allele of this gene (recessive) less MAO produced + ∴ higher levels of Serotonin. →more likely to be aggressive 
 


Question 6

related research to MAOA

Answer 6

MOFFITT 2002
SAMPLE: 442 m from New Zealand 

IV: Low // high activity allele of MAOA, Level of maltreatment in childhood (changes in caregiver, physical // sexual abuse)

DV: Antisocial behaviour (persistent fighting, lying, stealing, violent criminal behaviour)

METHOD: Longitudinal study (26 years)
RESULTS: pts who both suffered abuse + carried the MAOA-L gene were 9x as likely as the rest of the study group to engage in antisocial behaviour. 85% of seriously abused children with MAOA-L engaged in violent criminal behaviour. 
 

TS gene or environment alone there is no incr risk but the combination has an extremely bio deterministic effect 
→ Nature via nurture model. Nature (genes) is triggered by the environment 


BUT does not explain cultural differences

LEA: 56% of Maori men carry MAOA-L variation v.s to 34% of white men.
MAORI MOST GENETICALLY ISOLATED
TS cultural differences however have to be conscious on how it is used as this could be used as a justification of racism. Just because they have this gene does not make them more aggressive as MOFFITT suggests.