Genetic Explanations - Chromosomal Abnormality And Twin Research

Question 1

XYY Syndrome description

Answer 1

Abnormality with sperm production which can result in a male ending up with XYY - these males are known as ‘Supermales’

Question 2

Why are people (always male) with XYY syndrome known as ‘supermales’?

Answer 2

More aggressive - more testosterone than typical males

Linked to criminality

Question 3

Characteristics of a person with XYY syndrome

Answer 3

• aggressive
• antisocial behaviour
• impulsive
• acne
• tall (6ft or above)
• lower muscle tone

Question 4

Jacob et al. (1965) - study

Answer 4

XYY - more aggressive
XYY in general population - 1 in 1000
XYY in prison population - 15 in 1000
XYY is disproportionately represented in prison population vs general population

Question 5

Twin Research

Answer 5

Identical twins are used as a way of testing theories of criminality

Question 6

Monozygotic twins

Answer 6

Identical
1 egg splits in half
100% of DNA/genes shared

Question 7

Dizygotic twins

Answer 7

Non-identical
2 eggs released
50% of genes shared like normal siblings

Question 8

Why are identical twins (monozygotic) a good choice of participant if we are investigating whether crime is genetic?

Answer 8

If identical twins have 100% the same genes, and their behaviour is the same, it could be taken as evidence that genes cause behaviour
If one monozygotic (MZ) twin is a criminal, we would therefore wxpect the other to be.
If behaviour is different despite having 100% the same genes, then this suggests that criminality is not genetic

Question 9

Concordance definition

Answer 9

How much agreement there is between two factors

Question 10

High concordance

Answer 10

Both similar e.g. both identical twins are criminal (expected by this theory)

Evidence suggests that concordance rates are higher in identical twins than non-identical

Question 11

Low concordance

Answer 11

Both different e.g. one twin is criminal whereas the other is not