Zusammenfassung der Ressource
Genetic Factors
- Twins
- Monozygotic
Anmerkungen:
- Dizygotic
Anmerkungen:
- Studies
Anmerkungen:
- Compare degree of similarity for a specific trait between sets of monozygotic twins to similarity between sets of dizygotic twins.
- If MZ twins more alike in terms of aggressive behaviour, due to genes.
- Studys specifically studying aggressive behaviour using adult twins found a 50% variance in direct aggressive behaviour attributed to genetic factors.
- Adoption
- Study
Anmerkungen:
- Positive correlation between aggressive behaviour in adopted children and aggressive behaviour in biological parents=genes.
- Denmark
Anmerkungen:
- Study of over 14,000 adoptions in Denmark found significant number of adopted boys with criminal convictions had biological parents with the same.
- Low ecological validity as only looks in Denmark
- MAOA
Anmerkungen:
- Regulates metabolism of serotonin in brain, and low levels of serotonin is associated with impulse and aggressive behaviour.
- Brunner et al
Anmerkungen:
- 1980s. Dutch family found many of its aggressive male members to be involved in serious crimes.
- Due to abnormally low levels of MAOA, in which a defect was later found.
- Caspi et al
Anmerkungen:
- Linked MAOA to aggressive behaviour. 500 male children. A variant associated with high MAOA, and variant with low MAOA.
- Low=more likely to be aggressive, but only if they were maltreated as a child. Otherwise there was no aggression.
- Suggesting an interaction between genes and environment determines behaviour.
- Miles and Carey
Anmerkungen:
- Meta-analysis of 24 twin and adoption studies that supported link between genes and aggression.
- Most relied on self-report, with some observation. Results=strong genetic influence accounted for 50% variance in aggression.
- Found that age differences is important, later ages the influence of environment decreased, but genes increased.
- Individual Differences
Anmerkungen:
- Those observational ratings were more environmental influence.
- Convicts
Anmerkungen:
- Many studies focus on individuals convicted of violent crimes. 2 problems wrong with this.
- 1. They only represent a small minority, as convictions of violent crimes for more than one instance is rare.
- 2. May not be the most serious criminals, just labelled violent.
- Walters
Anmerkungen:
- Meta-analysis. Found low to moderate correlation for link between heredity and crime.
- Thus, inconclusive evidence.
- IDA-RWA
Anmerkungen:
- Genetic engineering if we're prediposed to aggression. Thus, an awareness of limitations of these studies is important.
- IDA-Animal Research
Anmerkungen:
- Young et al-genetic mutation violence in mice. Effects include violence towards other mice. Counterpart to gene in humans.
- Cannot generalise to humans.