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Psychology - RMC - Aggression > 2 - Genetic Factors In Aggression > Flashcards

2 - Genetic Factors In Aggression Flashcards

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1
Q

What are genetic factors?

A

Causal factors related to genes (made up of DNA strands) producing instructions for an organism’s physical + psychological features

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2
Q

What are the 2 ways of studying genetic factors in aggression?

A
  • Twin studies

- Adoption studies

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3
Q

What do twin studies do?

A

Compare traits of MZ + DZ twins to assess the role of genetic heritability in aggression

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4
Q

What are MZ twins?

A

Identical twins that share 100% of genes

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5
Q

What are DZ twins?

A

Non-identical twins that share 50% of genes

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6
Q

What have twin studies suggested about the cause of aggression?

A

Genes account for approx 50% of variance in aggression

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7
Q

If MZ twins are more alike in terms of aggression levels than DZ twins what does this suggest?

A

Aggression is dictated by genetics (nature) not the environment (nurture)

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8
Q

What is the research support for twin studies identifying a genetic influence on aggression?

A

Coccaro et al

  • Studied MZ + DZ twins raised in same environ
  • Physical assault concordance rate: 50% in MZ + 19% in DZ
  • Suggests genetics play a role in aggression
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9
Q

What do adoption studies do to look at genetic factors in aggression?

A

Look at similarity in aggression between adopted child + biological parents/adoptive parents

  • Similarities between child + biological -> genetic influence
  • Similarities between child + adoptive -> environmental influence
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10
Q

What have adoption studies suggested about the cause of aggression?

A

Genes account for approx 40% of variance in aggression

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11
Q

What is the research support for adoption studies identifying a genetic influence on aggression?

A

Mednick + Hutchings

  • Studied 14,000 adoptions in Denmark
  • Looked at boys with criminal convictions
  • Significant number had biological parents with criminal convictions
  • Suggests genetics play a role in aggression
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12
Q

What is the main genetic factor we look at in influencing aggression?

A

MAOA Gene

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13
Q

Is MAOA a gene or enzyme?

A

Gene

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14
Q

Is MAO-A a gene or enzyme?

A

Enzyme

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15
Q

What does MAOA gene do?

A

Controls production of MAO-A enzyme (which regulates serotonin production - which influences aggression levels)

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16
Q

What does MAO-A enzyme do?

A

Regulates the neurotransmitter serotonin - which plays a role in impulsive aggressive behaviour

17
Q

How is the MAOA gene thought to cause aggression?

A

MAOA-L (low activity variant of MAOA gene) results in low activity MAO-A enzyme + low serotonin levels, linked to high aggression levels

18
Q

What are the 2 variants of the MAOA gene + which is linked to aggression?

A

MAOA-H (high activity - NOT linked to aggression)

MAOA-L (low activity - linked to aggression)

19
Q

What is another word for the MAOA-L gene variant? Why?

A

‘Warrior gene’
Research by Lea + Chambers
- Studied MAOA-L in NZ
- Found the gene variant in 56% male Māoris + only 34% Caucasians
- Nicknamed ‘warrior gene’ because of Maoris’ aggressive warrior history

20
Q

What is the research to support the role of MAOA in aggression?

A

Brunner

  • Studied large Dutch family (28 males with history or rape, violence, impulsive aggression, learning disabilities)
  • These men had the MAOA-L variant
  • Concluded that this gene is likely to cause aggression + learning disabilities in males
21
Q

What proportion of western males have the MAOA-L variant?

A

1/3

22
Q

What is the GXE Interactions theory?

A

Theory that genetics only cause aggression when combined with environmental factors

23
Q

What model does the GXE theory fit?

A

Diathesis-Stress Model

24
Q

What is the Diathesis-Stress Model for aggression?

A

Diathesis + Stress = Aggression

  • Diathesis = MAOA-L gene variant
  • Stress = Traumatic early life experiences (e.g. abuse)
25
Q

What research supports the GXE Interactions approach to aggression?

A

Frazzetto et al

  • Found association between high antisocial aggression + MAOA-L variant in adult males
  • This association was only found in those who experienced trauma in first 15yrs of life
  • Suggests a genetic vulnerability isn’t enough to cause aggression
26
Q

Give 4 evaluation points for genetic factors in aggression

A

POS:
Multiple research for central genetic factor (MAOA-L gene)
- Brunner + Lea and Chambers support
- Mertins et al falsified theory (found MAOA-H ppts were less aggressive + more cooperative in a money distributing game)

NEG: 
Issues with twin studies
- May lack internal validity 
- Equal environments assumption 
- If MZ twins are treated more similarly, higher concordance of aggression may be due to this not genetics

Low understanding of how MAOA-L increases aggression

Recognition of environmental role

  • Genetics as an individual cause isn’t strong
  • Research by Frazzetto et al influences environmental importance too

Psychology - RMC - Aggression (4 decks)

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