Outline and evaluate genetic factors in aggressive behaviour

Outline and evaluate genetic factors in aggressive behaviour

1. AO2

   • Coccaro only indicates a possible component as they can’t find a specific gene or mechanism by which environment could overcome the predisposition
   • Miles & Carey ’97
     • Meta-analysis of 24 twin adoption studies that support genetic basis. Most relied on self report, so issues with social desirability etc.
   • Rhee & Waldman ’02
     • Meta-analysis of 51 studies. Aggression & antisocial behaviour is mostly due to genes, but can be influenced by age etc.
   • Young et al ’02
     • Researchers claim to have found a mutation of genes that causes extreme violence in mice. A human equivalent does exist, but not enough research has been carried out to form a causal relationship yet.
   • Methodology: many studies don’t consider if the crime is violent or not. They also don’t consider if the violence is habitual

2. AO1

   • Coccaro ‘97
     • Aggression in adult twins was studied. 50% of direct aggression could be due to genes
   • Hutchings & Mednick ’75
     • Looked at 14,000 Danish adoptions of boys with criminal convictions. Significant number of those boys’ biological fathers also had convictions
   • Montreal University
     • 667 mono & dizygotic twin pairs. Mothers asked to rate aggression (e.g. kicking, hitting) at 20,32 & 50 months old. Supported genetic maturation hypothesis as environment has short term effect whilst genes have a long term effect. Supports idea that people learn alternatives to aggression as they age
   • Brunner ’93
     • Dutch family, many men were violent, had faulty MAOA gene which regulates metabolism of serotonin. Low MAOA = ↑ impulsivity
   • Caspi ’02
     • 500 boys had low MAOA, ↑ likely to grow up & be anti-social only if maltreated as children. Shows interaction between environment and genes
   • Brenan & Mednick ’93
     • Genetic influence important on property crime but not violent crime in adopted kids

3. IDA

   • Animal studies
     • Might be unethical but can allow more in depth research on specific genes in the mice, which have an equivalent in humans
   • Real life application
     • It's been suggested that those with genetic dispositions to violence could be genetically engineered to remove the 'threat' of their violence, however this is very controversial