Biological explanation: Genes

Question 1

Explain the genetic explanation using Christiansen’s twin study.

Answer 1

• Studied over 3500 twin pairs in Denmark.
• Found concordance rate of 35% for MZ males and 13% for DZ males.
• Supports the genetic approach.

Question 2

Explain the genetic explanation using Crowe’s adoption study.

Answer 2

• Found that children who had a biological mother with a criminal record had a 50% risk of having a criminal record by 18.
• Those who didn’t have a mother with a criminal record, only had a 5% risk.

Question 3

What is the MAOA gene and how is this linked to offending?

Answer 3

It regulates serotonin in the brain and has been linked to aggressive behaviour.

Question 4

How can the diathesis-stress model be used to explain offending?

Answer 4

It shows that a combination of genetic predisposition and a biological/psychological triggers can cause the behaviour.

Question 5

What is a candidate gene with reference to offending?

Answer 5

A gene that predisposes someone to committing a crime.

Question 6

One limitation of twin studies is assuming equal environments.

Answer 6

• It’s often assumed that environmental factors are the same for MZ and DZ twins because they experience similar environments.
• However, because MZ are identical, people often treat them the same impacting their behaviour.
• Therefore higher concordance rates for MZ may be because they are treated more similar, suggesting conclusions may be less valid.

Question 7

One strength is the support for the diathesis-stress model of offending.

Answer 7

• Mednick et al studied 13,000 Danish adoptees having at least 1 conviction.
• Conviction rates were 13.5%(when bio or adopted parents had no convictions), 20% (when bio parent had a conviction) and 24.5% (when both bio and adopted parents had a conviction).
• Suggests both genetics and environment influence criminality.

Question 8

One limitation is that there are also issues with adoption studies.

Answer 8

• Adoption studies allow us to seperate nature and nurture, due to similarities from biological parents only being genetic.
• However, some are adopted late so spend their infancy with their bio parents anway, with some maintaining contact.
• This means the parents may have had an environmental rather than biological impact.