Biological Explanations for Criminality
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If criminology is biologically determined what should be exhibited?
Some genetic concordance
Which studies are used in order to investigate the genetic basis for criminality?
Twin and adoption studies
When investigating Monozygotic and Dizygotic twins, if criminality is genetic, what should be observed?
Higher concordance in Monozygotic twins as they share 100% of their genes
What was the aim of Lange's study in 1929?
To investigate the extent to which identical twins might differ from non identical twins with regards to criminal behaviour
What was the method employed in Lange's study of 1929?
- 13 pairs of MZ twins were studied with regard to a number of criminal indicators (possessing criminal record etc)
- These were compared to 17 pairs of DZ twins
What were the findings of Lange's study in 1929?
- Concordance was much higher for MZ twins (77%)
- 12% concordance for DZ twins
What can be concluded from Lange's study in 1929?
- The higher the degree of relatedness, the more likely the twin is to display the same behaviour as the other
- Criminality appears to be in the genes
What fact do twin studies tend to neglect?
MZ twins are more likely to have a shared environment when growing up
What did Christiansen find in 1977?
- MZ showed 35% concordance
- DZ showed 12%
Why are low concordance rates an issue for twin studies?
If criminality is truly genetic then 100% concordance rates should be seen
How can early twin studies be criticised on reliability?
- Judgments on zygosity were based on appearance rather than DNA testing
- May yield unreliable data as some members of the sample might not be twins
Why might criminality within a family not necessarily indicate a 'criminal gene'?
Criminality may be due to inherited emotional instability, mental disorders or poverty
How are adoption studies used to investigate a genetic basis for criminality?
- The behaviour of adopted children is compared with that of their biological parents and adoptive parentsIf there is a greater similarity between adoptee and biological parent then there must be a genetic component
What was the aim of the Mednick et al study of 1984?
To investigate the her heredibility of criminal behaviour in adoption studies
What methods were employed during the Mednick et al study of 1984?
- Information from a Danish adoption bank was used that covers the social histories of over 14,000 children
- The criminal conviction rates were compared to that of their biological parents
What were the results of the Mednick et al study of 1984?
- 20% whose biological parents had convictions had convictions themselves
- 13.5% whose biological parents did not have convictions had convictions
What did Crock find in 1972?
- 50% of children in a sample of adoptees whose mothers had a criminal record had one themselves by 18
- Only 5% of children whose mothers didn't have a record had one themselves
Why might the time of adoption affect the biological theory?
- Children are rarely adopted at birth
- Many studies involved children that experienced late adoption
- It is difficult to know how their early experiences may have affected their development
Why might the maintained contact between adopted children and their biological parents affect the findings of adoption studies?
- Children may still be influenced by their biological parents
- May model themselves on their biological parents rather than their adopted ones
Why might matching of biological and adopted parents affect adoption studies?
Adopted parents may be similar in characteristics, still promoting violent behaviour and the tendency to commit crime, much like their biological parents
What did Jacobs et al state in 1965?
- Males with an extra Y chromosome were typically more aggressive and violent and it was this factor that led to them becoming criminals
- 15% of prison population had an extra Y
- Only 0.1% of the general population have an extra Y
Why is the XYY theory no longer accepted?
- There were issues in identifying the abnormal gene, often this was incorrectly identified
- Minimal differences were found between other violent offenders in prison who lacked the XYY anomaly (Hollins 1989)
- Witkin et al (1976) found that 12 men in a sample of 4500 had the extra Y chromosome and none of which had been an offender
What evidence has animal research uncovered regarding neurophysiology?
Areas in the brain such as the limbic system and the amygdala are responsible for aggressive behaviour, although this aggression requires environmental stimulus
What have studies of people with APD shown?
- Antisocial personality disorder (psychopathy)
- Individuals have had a slow wave activity, typical of brain immaturity
What is the maturation retardation hypothesis?
- The brain of a person with APD is childlike and hasn't matured
- This leads to impulsive, aggressive behaviour and the inability to delay gratification resulting in criminal tendencies
What did Raine et Al find in 2000
- Compared the brain volume of people with APD to controls using an MRI to measure the prefrontal grey and white matter
- Autonomic activity was also measured in a stressful situation
- A reduced amount of grey matter (11%) was found in the brains of individuals with APD as well as reduced autonomic responses
What can be concluded from Raine et al's study?
- There is a structural brain defect in people with APD
- May cause APD behaviour such as poor arousal, lack of conscience and poor fear conditioning
What does the biological approach take into account about the criminal that other approaches do not?
Personality differences that might exist from birth such as impulsiveness and desire for excitement
What do biological theories help us understand about the childhood of criminals?
They may cause such problems as poor achievement in school and inadequate socialisation which may turn to criminality
Why is the use of animal studies a weakness of the biological theories?
We cannot generalise findings from the brains of animals such as mice to human brains, ours are far more complex and may function differently
How is the biological theory reductionist and how is this a problem?
- Complex behaviour such as offending is explained by the underdevelopment of brain structures
- This ignores all other factors that could be causing this behaviour such as the environment
How are the biological explanations too deterministic?
- They assume people are controlled by biological influence and lack of free will.
- This fails to take into account the cognitive decisions that are made by offenders
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