Biological explanation for criminality
Twin studies- Research into the similarity of twins particular their criminal similarity, to investigate genetic links.
Twin studies- Monozygotic twins share exactly the same genes. Christiansen (1977) found that from 3586 pairs of twins if an identical twin was a criminal, 525 of the time the other twin was also a criminal. In diagnostic twins the rate was only 22%.
We can also look at adoption studies- these people share genes nut not environment so in these cases we can be sure that genetics are the cause of criminality.
XYY- A rare genetic pattern said to be linked to aggression and slow learning ability.
XYY (male) chromosome abnormality- Causes increased aggression, being taller and learning difficulties.
However, just a handful of murderers have been found to have XYY. We cannot find enough samples of people with the disorder to be certain of the link to violent crime.
Chromosome abnormality- A mutation of genetic material that results as a change in the number or structure of chromosomes.
Theilgaard (1984) The criminal gene
Aim- Wanted to see if criminals had a particular gene that could be responsible for their criminal behaviour.
Procedure- They took blood samples from over 30,000 men. They were interviewed by a social worker
Results- It is found that XYY males had slightly lower intelligence than average and were more aggressive. However no solid of a criminal gene was found.
Conclusion- This study provides limited evidence for XYY males being more aggressive than XYY males.
Strengths- No researcher or interviewer was bias and used a vast range of tests to measure their aspects of life.
Weaknesses- only a small sample was used and the link between XYY males and aggression is only a correlation.
Social explanation for criminality
The way in which parents bring up their children are known as childrearing strategies. Dealing with naughty children may involve induction, love withdrawal and power assertion.
Induction- Where parents explain to their child what they have done wrong and allow them to think about the consequences.
Love withdrawal- Where parents put conditions on their love, they don't love their children when they have one something bad. Results in children being confused about their identity, unsure as to whether they are loved or not.
power assertion- Includes hitting, shouting at children, humiliating them and can lead to aggression.
Self-fulfilling prophecy- When the expectations of others influence our behaviour.
Sigall and Ostrove (1975) Attractiveness and jury decision making:
Aim- To see whether attractiveness affected jury decision making and to investigate whether there was a relationship between attractiveness and the type of crime committed.