biological explanations: genetic and neural evaluation

Question 1

issues with twin studies

Answer 1

POINT: One limitation with using twin studies as genetic evidence is that the assumption of equal environments

EVIDNENCE: It is assumed by researchers studying twins that environmental factors are held constant because twins are brought up together and therefore must experience similar environments

EXPLANATION: However, this shared environment assumption may apply much more to ,Z twins than DZ twins because MZ twins look identical and people (especially parents) tend to treat them more similarly which in turn affects their behaviour

Therefore higher concordance rates for MZs in twin studies may simply be because they are treated much more similarly than DZ twins

Question 2

support for diathesis stress

Answer 2

POINT: one strength is support for the diathesis stress model of offending

EVIDENCE: A study of 13,000 Danish adoptees was conducted by Sarnoff Mednick et al (1984.
When neither the biological nor adoptive parents had convictions, the percentage of adoptees that did was 13.5%. The figure rose to 20% when either of the biological parents had convictions, and 24.5% when both adoptive and biological parents had convictions

EVIDENCE: This shows that genetic inheritance plays an important role in offending but environmental influence clearly is also important, providing support for the diathesis stress model

Question 3

Brain evidence: neural explanation

Answer 3

POINT: One strength of the neural explanation is support for the link between crime and the frontal lobe

EVIDENCE: Elizabeth Kandel and David Freed (1989) reviewed evidence of frontal lobe damage (including prefrontal cortex) and antisocial behaviour
People with such damage tended to show impulsive behaviour, emotional instability and inability to learn from their mistakes.
The frontal lobe is associated with planning behaviour

EXPLANATION: This supports the idea that the brain damage may be a causal factor in offending behaviour

Question 4

intervening variables

Answer 4

POINT: One limitation is the link between neural difference and APD may be complex

EVIDENCE: Other factors but contribute to APD, and ultimately to offending
David Farrington et al studied a group of men who scored high on psychopathy (APD).
These individuals had experienced various risk factors during childhood, such as being raised by a convicted parent and being physically neglected. It could be that these childhood experiences caused