Zusammenfassung der Ressource
Biological explanations of
criminality
- Family studies
- You compare family trees of
criminals and non criminals
- The child is more likely to become criminal if
their grandparents or parents are
- You can't separate the biological
factors from the environment
- Adoption studies have been
more successful
- Mednick 1984
- Studied 14,427 adopted children and
compared their criminal records with those
of both adopted and biological parents
- Those who have criminal records for theft have biological
fathers with the same record even if separated
- It showed that some criminal behaviour is
influenced by biological factors
- Twin studies
- Christiansen 1977
- Studied 3586 twins in Denmark
- He found if an identical twin was a criminal 52% of
the time their twin was also criminal
- He found that with non identical twins if one twin
was criminal only 22% of the time their twin was also
criminal
- Theilgaard 1984
- Wanted to see if criminals had a gene that was
responsible for their criminal beahaviour
- Studied 30,000 men born in the 1940's
- Theilgaard took blood samples from the 30,000 and analysed the 23
pairs of chromosomes each person has
- From 30,000 only 16 were found to have the XXY
abnormality and 12 had the XYY abnormality
- The final twelve were then examined
- The 12 were interviewed by a social worker who didn't
know the aim of the study about their background and
criminal history
- The twelve were also given IQ tests
- The twelve were given personality tests
- The XYY males only had slightly lower levels of intelligence
than average
- They also tended to be more aggressive
- There were far more similarities
than differences between XXY and
XXY males
- The social worker didn't know the aim of the
study so that eliminated interviewer biase
- Theilgaard used a variety of tests to get her data. Which
improved the credibility of her results
- This was only tested on 12 men with the XYY out of 30,000 so
it's impossible to generalise it to all men who have the XYY
abnormality
- The links between XYY males and aggression is only a correlation so the chromosome abnormality may not be the cause of the increased aggression
- Not all XYY males were criminals and via versa