Biological Causes of Crime: XYY Syndrome

Question 1

How many pairs of chromosomes do humans have?

Answer 1

23

Question 2

What combination of chromosomes in the 23rd pair determines gender?

Answer 2

Male - XY

Females - XX

Question 3

What does XYY syndrome involve?

Answer 3

When a male receives an extra Y chromosome, resulting in 47 chromosomes instead of 46.

Question 4

How often does it occur and what are the genetics?

Answer 4

1/1000 of every male birth and it is not inherited but instead it is a random occurrence.

Question 5

What are the affects of this condition?

Answer 5

• Some may grow taller and faster
• Some may have lower intelligence
• Some may have behavioural problems
• Some may be more physically active than others
• Some may lack empathy

Question 6

Why might XYY syndrome lead to criminal behaviour?

Answer 6

Behavioural problems may lead to impulsivity and so leading to criminal behaviour. Males who are more physically active may lead to anti-social behaviour.

Question 7

How does this affect gender and criminality.

Answer 7

Due to women having the pair XX it is impossible for them to gain two extra YY chromosomes to lead to XYY syndrome.

Question 8

Using the acronym ‘EACH’, evaluate 2 ‘evidence’ points.

Answer 8

P - Stockholm (2012) supports
E - Found that there was a significant increase in the number of convictions in a group of males with XYY compared to general incidences of crime in general pop
E - Therefore suggesting that having XYY syndrome correlates to criminal behaviour
P - Jacob et al (2012) supports
E - Found a link between XYY prison population, norm being 1/1000, here 15/1000
E - This over representation shows higher than normal in criminals

Question 9

Using the acronym ‘EACH’, evaluate 2 ‘how’ points.

Answer 9

P - Cannot establish cause and effect
E - Only shows a relationship between having XYY syndrome and committing crimes
E - Therefore there may be other factors contributing to conviction rates such as socioeconomic background rather than genetics
P - Difficult to identify
E - There is no actual way of seeing chromosomes
E - And so it is putting a label on something that can’t be defined therefore diagnosis is difficult

Question 10

Are there any practical applications?

Answer 10

P - Yes
E - If the syndrome is found early (around 25% are found at birth) then issues of criminality can be addressed
E - This may prevent the labelling arising from the syndrome and therefore reducing the likelihood of a link with criminality

Question 11

Using the acronym ‘EACH’, evaluate 2 ‘criticism’ points.

Answer 11

P - Cannot account for all crime
E - XYY syndrome only affects males
E - Therefore it doesn’t explain why females commit crimes
P - Theilgaard (1984) found that XYY males had lower levels of intelligence
E - He argued that increased levels of crime may be due to the learning difficulties associated with the condition rather than the condition itself
E - Therefore suggesting that having the genotype XYY may not be a direct cause of criminality