Genetic Explanations of Offending (Year 13 Booklet 6)

Define genetic explanations as a biological explanation of offending behaviour.

Suggests that offenders inherit genes that predispose them to offending behaviour

How many genes are shared between:

• Monozygotic twins

• Dizygotic twins

• 100%

• 50%

What did Christiansen (1977) investigate and what did they find?

• Studied:

  • 87 Monozygotic Twin pairs

  • 147 Dizygotic Twin pairs

• Concordance rate of criminality

  • 33% Monozygotic Twins

  • 12% Dizygotic Twin

2 counter points for the genetic explanation of offending (Christiansen)

• Concordance rates for MZ twins not 100% → Shows environmental factor still plays a part in offending

• Confounding variable → MZ twins have more similar environmental experiences than DZ twins

Outline what a piece of adoption research found

• Crowe (1972)

• Findings

  • Adoptees who had a biological mother with a criminal record had a 50% chance of also having a criminal record by the age of 18

  • Adoptees who had a biological mother without a criminal record only had a 5% chance of having a criminal record by the age of 18

How could late adoption affect the results of Crowe’s research?

• Late adoptees spend more time with biological mother, therefore in environment with criminal behaviour

• Environmental factors could lead to criminal behaviour

• Genetic variable might not be the only variable being changed

What are candidate genes?

Specific genes thought to increase the risk of inheriting a characteristic

What research did Tiihonen et al. (2014) conduct and what did they find?

• Analysis of 900 Finnish offenders

• Found abnormalities within 2 genes was associated with violent crime

  • MAOA gene

  • CDH13 gene

• Found individuals with combination of both were 13x more likely to have a history of violent behaviour

What is the MAOA gene important for?

• Serotonin

• Aggression

What is the CDH-13 gene linked to?

• Substance abuse

• ADHD

Tiihonen et al.’s research has not been replicated. Why is this a problem?

• We cannot be sure if the findings are reliable

• Limits conclusions and usefulness of research

Give one limitation of Tiihonen et al.’s research

• Lack of control group

• What percentage of non-criminals have both genes?

What is the diathesis stress model?

Suggests whilst genetics will have an influence on offending, it is moderated by the role of the environment

How do twin studies support the diathesis/stress model?

• Twin studies concordance rates are not 100% in twins that share 100% genes

• So environment must play a role

Outline the findings of Medick et al.’s research as supporting evidence for the Diathesis/Stress model

• Studied over 13000 Danish adoptees

• Percentage of criminal adoptees

  • Neither biological or adoptive parents had criminal convictions: 13.5%

  • At least one biological parent had criminal convictions: 20%

  • Both biological and adoptive parents had criminal convictions: 24.5%

• Highest rates of criminality was when there was both diathesis and stress

• Supports the idea that to understand criminal behaviour we need to consider both genetic and environmental factors

How are the genetic + neural explanations biologically reductionist? Why is that a limitation of these explanations?

• They reduce complex human behaviour to biological factors such as genes, neurotransmitters and brain structures, ignoring social and environmental influences

• Offending is caused by many factors interaction, biological reductionism oversimplifies the causes

How are the genetic + neural explanations determinist? Why are the implications for this for the legal system?

• Suggest behaviour is caused by biological factors (genes, brain structure, neurotransmitters) that individuals cannot control, implying behaviour is predetermined.

• If behaviour is not in our control, this challenges the idea of free will and personal responsibility, potentially reducing criminal responsibility