genetic factors in aggression Flashcards

1
Q

genes

A
  • consist of DNA strands
  • DNA produces instructions for general physical features of an organism (e.g. eye colour, height)
  • also specific physical features (e.g. neurotransmitter levels)
    = can affect psychological features (e.g. mental health)
  • genes transmitted from parents to offspring = inherited
  • evidence shows that there is a link between genes + aggression
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2
Q

how is the link between genes + aggression shown?

A
  • twin studies
  • adoption studies
  • candidate genes
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3
Q

twin studies

A
  • studies looked at aggression displayed by MZ + DZ twins
  • study found that concordant rate for direct aggression (physical assault) :
    MZ - 50%
    DZ - 19%
  • concordant rate for verbal aggression:
    MZ - 28%
    DZ - 7%
    = shows that both verbal + physical aggression are high enough to suggest a genetic component for aggression
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4
Q

adoption studies

A
  • similarities in aggressive behaviour between an adopted child + their biological parents
    = suggest that genetic influences are operating
  • similarities between an adopted child + adoptive parents
    = suggest environmental influences are operating
  • psychs conducted a meta-analysis of adoption studies of direct aggression + anti-social behaviour
    = found that genetic influence accounted 41% of these
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5
Q

candidate genes

A
  • specific genes have been identified which have been shown to carry the aggression trait down to individuals
  • MAOA L gene:
  • ‘warrior gene’
    = dysfunction of MAOA gene
  • too much adrenaline = hypersensitivity in the FoF response
  • too much dopamine = aggressive behaviour
  • low levels of serotonin = reduction of control over impulsive behaviour

= leads to aggressive behaviour
- psychs found that this gene was possessed by 56% of New Zealand Maori men compared to 34% Caucasians

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6
Q

neurotransmitter levels + consequential behaviour - candidate genes

A

high dopamine levels = increases likelihood of reward when aggression is carried out

low serotonin levels = lack of inhibition over impulsive behaviours

high noradrenaline levels = overreaction to perceived threats

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7
Q

ads of genetic factors

A
  • research support
  • selective breeding
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8
Q

disads of genetic factors

A
  • XYY
  • twin studies validity
  • biological determinism
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9
Q

research support - ads of genetic factors

A
  • lots of research support for the genetic explanation
  • psych found the concordance rate of physical aggression in the form of criminal behaviour for MZ twins was much higher than DZ twins
    = suggests that the role of nature plays a strong role in aggression
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10
Q

selective breeding - ads of genetic factors

A
  • scientists have refined selective breeding
  • specifically removed the MAOA gene in mice
  • mice showed increased aggression + abnormal levels of serotonin
    = demonstrates the relationship between genes + neurotransmitters
  • when the mice were given fluoxetine to raise serotonin levels
    = behaviour returned to normal
    = study supports the role of genetics, especially the MAOA gene, in aggression
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11
Q

XYY - disads of genetic factors

A
  • not all research supports the role of genetic factors for aggression
  • e.g. psych undertook research into men w/ XYY genotype
  • found that XYY can cause na increase in height but not an increase in aggression
    = shows we can’t make generalisations about aggression
    = there is no link between XYY + aggression
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12
Q

twin studies validity - disads of genetic factors

A
  • the use of twin studies may lack validity
  • in every pair of twins = share the same environment
  • HOWEVER, DZ twins may not share the same environment to the same extent as MZ twins
  • e.g. MZ twins treated by parents + significant others the same way as they’re identical
  • but DZ won’t, especially if they’re different sex
    = MZ twins have identical genes + environment = contribute to their aggression compared to DZ twins
    = twin studies research lacks validity
    = not only measuring genetic influence on aggression
    = but also unintentionally measuring environmental influences

(nature vs nurture)

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13
Q

biological determinism - disads of genetic factors

A
  • doesn’t take into account free will
  • up to hormones
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