Outline and evaluate genetic factors in
aggressive behaviour
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
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
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