Genetic factors in aggression

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  • Created by: millie
  • Created on: 06-06-15 20:53
What is the main question involved in establishing the genetic factors in aggression?
Nature (genetics) or nurture (environment)
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How are twin studies used to investigate the genetic factors in aggression?
Look at similarities of aggressive behaviour in MZ twins(share 100% genes) and DZ twins(share 50% genes).If MZ twins are very alike in aggressive behaviour, this displays genetic factor in aggression rather than environmental
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What did Coccaro do in their twin study on aggressive behaviour?
Looked specifically at aggressive behaviour rather than most commonly used criminal behaviour, in adult twin pairs finding almost 50% of variance in direct aggressive behaviour could be linked to genetic influences
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Why are adoption studies used to study genetic factors in aggression?
Makes it easier to separate between genetic and environmental contributions to aggression
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How are adoption studies used to study the genetic factors in aggression?
If a positive correlation is shown between adopted child's aggressive behaviour & biological parent's aggressive behaviour this suggest genetic influence
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Continuation of how adoption studies to study genetic factors in aggression...
If positive correlation is found between adopted child's aggressive behaviour and adopted parent's aggressive behaviour, this supports an environmental influence for aggression
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What did the adoption study in Denmark do and what did it find?
Studied 14,000 adoptions, found significant number of adopted males with criminal convictions had biological parents who also had criminal convictions. This suggests genetic influence to aggression
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What genes are thought to cause aggression?
No genes have been identified as the root cause but there is a gene responsible for the production of MAOA which is something that regulates metabolism of serotonin (low levels of serotonin linked to aggressive & impulsive behaviour)
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What was found in a Dutch family in relation to aggression?
Male members of a Dutch family had aggressive & impulsive manner,in addition many had been part of serious violent crimes such as **** & arson. These members had significantly low MAOA levels which was later identified to be due to gene defect
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Instead of gene or environment being a factor of aggression, what is another possible factor?
Gene-environment interaction
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What did Capsi et al. do in their study on gene-environment interaction as a factor of aggression?
Looked at link between MAOA & aggression in 500 male children, found variant of gene that causes low MAOA & variant linked with high levels
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What did Capsi et al. find in their study on gene-environment interaction as a factor of aggression?
Those with low levels of MAOA & maltreated as children were more likely to display antisocial behaviour.Those with high levels who were also maltreated or those with low levels who were not maltreated not likely to show antisocial behaviour
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What have adoption studies shown in relation to gene-environment interaction?
Highest rates of criminal violence was most likely to occur when both biological and adoptive parents were criminally violent showing joint genetic and environment contribution
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What is a weakness in genetic explanations of aggression?
Determining link between genetic factors & aggression is not straightforward as it's difficult to know what's produced by genetics/what isn't.A few reasons why it's hard: more than 1 gene usually contributes to a behaviour & influences can interact
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What is meant by it being difficult to establish the link between genetic factors & aggression because influences can interact?
Genetic factors may cause other environmental factors to impact the aggression
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What is a weakness of twin studies?
Lack validity-many twins studies don't take into account fact that identical twins share more environmental similarities than DZ twins such as fact that MZ twins are more likely to be put in same school class as each other
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Continuation of weakness of twin studies...
Shows that similarity findings of aggression in MZ twins may be more associated with environmental factors than genetic factors of aggression resulting in argument for genetic influence being weaker and giving a lack of validity in studies
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What is the debate of the genetic approach to aggression?
Reductionist-tries to reduce complexity of aggression into simple,measurable gene factor.Ignores other possible factors e.g social learning.Doesn't make it wrong, just not complete explanation
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What is a weakness in the amount of support there is for the genetic approach?
Inconclusive evidence for inheritance of criminal violence. Walter did meta-analysis of studies in area finding link between heredity & violence was usually low/moderate.Better/modern studies found less evidence for gene-crime hypothesis
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Continuation of weakness in the amount of support there is for the genetic approach...
More recent conclusion of recent studies suggested heredity was not a strong role in violence. These findings do not show straightforward conclusion of gene-crime hypothesis showing inconclusive evidence in area
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What is a weakness in the studies on the inheritance of criminal violence?
Methodological issues-studies on genetics influencing crime are not specific enough between what crime in violent/non-violent making it hard to establish how genetic factors specifically affect aggression.
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Continuation in weaknesses of studies on inheritance of criminal violence...
Additionally,they do not specify between habitually violent criminals and those whose crime is one-off. Tells us methodologies are problematic as affect how we can establish role of genetic factors in aggression
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How are twin studies used to investigate the genetic factors in aggression?

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Look at similarities of aggressive behaviour in MZ twins(share 100% genes) and DZ twins(share 50% genes).If MZ twins are very alike in aggressive behaviour, this displays genetic factor in aggression rather than environmental

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What did Coccaro do in their twin study on aggressive behaviour?

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Card 4

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Why are adoption studies used to study genetic factors in aggression?

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How are adoption studies used to study the genetic factors in aggression?

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