Aggression: Genetic Influences Flashcards

1
Q

Tests for genetic influence

A

Twin studies
adoption studies
epigenetics

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2
Q

Concordance rate

A

The probability a pair of individuals will both have a characteristic, given that one pair has the characteristic

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3
Q

What type of twin should concordance rates be higher in

A

Monozygotic as they share 100% of their genes

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4
Q

Twin studies

A

Similarity in aggressive tendencies should be higher in MZ twins than DZ twins because both sets of twins share the same environment.
However:
MZ share 100% of genes
DZ share 50% of genes

therefore any difference in concordance rate should be down to genes

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5
Q

McGuffin (1985)

A

Twin studies
Found MZ twins concordance rate for aggression 0.8 7
Found DZ twins concordance rate for aggression 0.72

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6
Q

Coracco (1997)

A

Twin studies
Found 50% of aggressive behaviour towards others is due to genetics
suggests a genetic underpinning
50% is high when considering other factors like deindividuation, Social learning, and institutional agg.
These may have an impact but much smaller in comparison to genetic influence

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7
Q

Adoption studies

A

Can I help determine the relative contributions of environments and hereditary aggression

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8
Q

How are adoption studies carried out?

A

Compare rates of aggression of adoptees with their biological parents. If strong concordance rate, suggests didn’t learn aggression through environment must have a genetic base

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9
Q

Hutchings and Mednick. Procedure

A

Adoption studies

Conducted large-scale adoption study Denmark 14,000 adoptees

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10
Q

Hutchings and Mednick. Findings

A

Adopted boys with criminal convictions in Denmark found to have biological parents mainly fathers with criminal convictions.
Supports genes are the cause of aggression rather than environment

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11
Q

Epigenetics

A

Changes in organisms, caused by modification of gene expression

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12
Q

MAOA gene in humans

A

humans have various forms of the MAOA gene, resulting in different levels of activity of the enzyme

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13
Q

What does MAOA do?

A

an enzyme

breaks down important neurotransmitters in the brain, including dopamine and serotonin;

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14
Q

Brunner et al 1993

A

MAOA gene
Dutch family - males were violent, aggressive criminals
Found the same genetic mutation which affected production of MAOA (has abnormally low levels of MAOA)
Therefore not producing enough serotonin leads to aggression

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15
Q

Brunner - criticism

A

One case study
Idiographic
Not generalisable

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16
Q

Caspi 2002

A

MAOA gene
Studies 500 male children and identified two variants of MAOA gene:
MAOA-H
MAOA-L

17
Q

MAOA-H

A

High levels of MAOA = low levels of aggression

18
Q

MAOA-L

A

Warrior gene
Low levels of MAOA, high levels of aggression BUT

nature-nurture interaction: Found children with warrior gene only became aggressive if they’d been maltreated as a child - Caspi

19
Q

Conclusion

A

Born with a predisposition for aggression, but environmental factors trigger it
diathesis stress model

20
Q

RWA x Ethics

A

Suggest people’s genes predisposition towards aggressive behaviour
Genetic engineering used to change genes and reduce risk
More extreme = chemical castration
Labelling individuals as dangerous based on genetic inheritance poses serious ethical questions

21
Q

Twin studies criticism

A

Theory that MZ twins share and environment to the same extent as DZ twins do, not necessarily true
MZ twins = more likely to be treated identically
DZ twins = more independent and gain individual identity

22
Q

MAOA is regulated by

A

the MAOA gene