AC 2.1 and 3.2 describe and evaluate Biological Theories

Question 1

XYY theory- Genetic theories

Cause of Criminality

Answer 1

• Women have XX chromosomes and men have XY chromosomes.
• XYY men have an extra chromosome- believed to be more aggressive.

Question 2

XYY theory- Genetic theories

Evidence to support

Answer 2

• Jacob et al suggested XYY men are more aggressive that XY.
• Prison studies showed 15 XYY men per 1000 in prison whereas 1 in 1000 in the general poulation.

Question 3

XYY theory- Genetic theories

Strengths

Answer 3

• Backed by Jacob et al study.
• Adler et al showed aggressive/violent behaviour paetly determined by genes.

Question 4

XYY theory- Genetic theories

Weakness

Answer 4

• Theilgard researched traits of XY men compared to XYY men- found no link to aggression in XYY men.
• Gentic abnormalities are widespread throughout the poplulation.

Question 5

Twin studies - Genetic theories

Cause of criminality

Answer 5

• People inherit criminality. Twin studies have taken place to try prove this- Monozygotic twins share 100% of their DNA whereas Dizygotic twins share 50%- the concordance rate of criminality in MZ twins is mush hugher than that in DZ.

Question 6

Twin studies - Genetic theories

Evidence to support this

Answer 6

• Lange’s study showed 10/13 MZ twins have both been in prison whereas only 2/17 DZ twins had.
• Christiansen’s study found a concordnace rate of 35% for male MZ tiwns and 13% for male DZ twins.

Question 7

Twin studies - Genetic theories

Strengths

Answer 7

• Christiansen’s study supports genetic link to criminality.
• Such studies are natural experimanets rather than constructed purely for research.

Question 8

Twin studies - Genetic theories

Weakness

Answer 8

• Early twin studies such as Lange were inadeuqately controlled- decided which were MZ and DZ twins based on appearance and not DNA.
• Small sample in twin studes may not be representative of te general popluation.