AC 2.1 Biological theories

Question 1

Biological theories
- Genetic theories
- Jacobs XYY study

Answer 1

Main Points:
- XX = female, XY = Male, XYY = supermale(more aggressive and violent)
- XYY behaviours include:
explosive temper,
hyperactivity,
impulsivity,
defiant actions,
lack of empathy, and,
in some cases, antisocial behaviour

Study:
- Jacob et al - Found that 15/1000 in prison , 1/1000 in the general population.
CASE STUDY - JOHN WAYNE GACY - sexually assaulted, tortured and murdered at least 33 men in the USA(may have had XYY)

Question 2

Biological theories
- Genetic theories
- Twin and adoption studies

Answer 2

Main Points:
- Monozygotic Twins - Born at the same time but come from one egg and share 100% of the DNA. (Identical Twins)
- Dizygotic Twins - Born at the same time but come from two separate eggs and share 50% of the DNA. (Fraternal Twins)
- Concordance Rates:
The probability (as a percentage) that if one twin has a characteristic the other twin will have the characteristic.
- it is thought if one monozygotic twin is a criminal the other ought to be as well

Study:
Johannes Lange
- Investigated 13 MZ twins and 17 DZ twins.
- 10/13 MZ twins had both served time in prison.
- 2 of 17 DZ twins had both served time in prison.

Christensen
- Criminal tendencies concordance rate
- Investigated 3586 twin pairs born in the eastern half of Denmark between 1881 and 1910
- 52% concordance rate between MZ twins.
- Non-Identical twins (Dyzgotic) there was only a 22% chance.

Question 3

Biological theories
- Genetic theories
- Lombroso

Answer 3

Main points:
- Born criminal based of physical
features
- Long arms, large teeth, ears
lacking lobes, lots of body hair
- Murderers had bloodshot
eyes
and curly hair
- Sex offenders had thick lips
and protruding ears

Study:
- He based this on data gathered
from autopsies on convicted
criminals.
- university in China- ID photos
of 1856 Chinese men, half of
whom had a previous
conviction, were entered into
an artificial intelligence
programme.

Results:
- They found it wrongly flagged innocent men as criminal 6% of the time, but correctly identified 83% of the real criminals.

Question 4

Biological theories
- Genetic theories
- Sheldon

Answer 4

Main Points:
- Three basic body types and
associated temperaments and personalities
- Ectomorphic (thin and fragile) are introverted, restrained and sensitive
- Mesomorphic (muscular and hard) tend to be aggressive and adventurous.
- Endomorphic (fat and soft) tend to be extroverted / sociable and relaxed.

Study:
- Mesomorphs are most likely to
engage in crime
- to be attracted by the risk-taking it involves.
- Ectomorphs are the least likely criminals

• photographs of college students
• scale of 1 (low) – 7 (high) their resemblance to mesomorphy

Results:
- delinquents had a higher average mesomorphy when compared to that of college students