2. Aim
A case study on a family from the Netherlands where
males were affected by a syndrome of borderline
mental retardation and abnormal violent behaviour.
These included impulsive aggression, arson, attempted
rape and exhibitionism.
3. Procedure
The sample was of 5 males who had the same genetic
condition which was later called Bruner syndrome. Two
carrier females and one non-carrier females were used
as a control group.
Samples of urine for each of the participants were
collected and analysed over a 24 hour period.
4. Results
The data showed a disturbed monoamine metabolism
which is associated with a deficit of the enzyme
monoamine oxidase A (MAOA). A mutation was found in
the X chromosome of the gene responsible for the
production of MAOA which is why only males were
effected.
5. Link to crime
It is likely that the defect in the gene which causes
flawed serotonin metabolism is the cause of the mental
retardation and the aggressive behaviour exhibited in
the males. The MAOA deficiency accounts for their
inability to regulate their aggression which could lead to
them committing criminal acts.
6. issues
Generalisability A very small sample of only 5 males
was used which makes it difficult to apply this study to
real life. Also it was found that this gene is very rare
and only effects males so does not explain why other
males, who aren’t effected, and women turn to criminal
activity.
Usefulness The study shows that criminal behaviour
can be genetic and that it is not always to do with the
way we are brought up (social).
Application We can use the information found from
this study to identify families who carry this gene and
give them the support they need before they turn to
crime.
7. Debates
Internal Determinism The study shows that criminal
behaviour is not always down to free will, in some cases
people are more likely to turn to crime because of their
genetic make up. Having a mutation in one of your
genes can increase the possibility of someone turning to
a life of crime.
Individual The study explains criminal behaviour as
being down to the individual, not the situation in which
they have been brought up. It says that it is down to a
mutated gene that certain people participate in
criminal activity.
8. Quiz Questions
1. Where were the effected family from?
2. What did the illness become known as?
3. Why were only males effected?
4. How was data collected?
5. Why can the results be considered objective?
9. Answers
1. The Netherlands.
2. Bruner Syndrome.
3. The mutation was in the X chromosome.
4. Through a urine sample.
5. Specialist equipment was used.
