Genetic factors in aggression

Question 0

How is it associated with aggressive behaviour

Answer 0

MAOA regulates serotonin levels in the brain. Low levels of serotonin are associated with anti social behaviour such as impulsivity and aggressiveness.

Question 1

Is there a gene for aggression.

Answer 1

No but gene for producing MAOA has been found which is associated with aggressive behaviour

Question 2

Any evidence.

Answer 2

A Dutch study found many of its family members had all be associated with aggression and violent crimes. These men were found to have low levels of MAOA.

Question 3

Is it genes alone?

Answer 3

No. A study found that only children with a defect gene for MAOA that had been mistreated as well were to grow up and show signs of aggressive behaviour. This shows an interaction between genes and environment that determines behaviours such as aggression

Question 4

Where did these ideas come from?

Answer 4

Twin and adoption studies.

Question 5

Twin studies

Answer 5

Identical twins share all same genes
Non identical twins share half.
Concordance rates were measured and if down to genes alone identical twins should show 100% similarity in aggressive behaviour and 50% for non identical
Higher rates found in identical than non identical
This supports the study that genes have influence on aggressive behaviour

Question 6

Adoption studies

Answer 6

If correlation between aggressive children and aggressive parents is found. Genetic effect is implied
If correlation between aggressive children and aggressive and rearing family then environmental effect implied
14,000 adoptions in Denmark found criminals who had been adopted had criminal fathers. Supporting genetics