genetic explanations of offending

Question 1

give the numbers of participants and the findings from Lange’s research (1930)

Answer 1

13 MZ twins and 17 DZ twins where one of the twins in each twin pair had spent time in prison

10 of MZ twins but only of 2 of DZ twins had a co twin that had also spent time in prison suggesting there is a genetic link

Question 2

give the numbers of participants and the findings from Christiansen’s research (1977)

Answer 2

studied over 3500 Danish twin pairs finding concordance rates for offender behaviour

35% MZ twin males and 13% for non - identical twin males with a slightly lower rate for females

suggesting offending may have a genetic component

this was supported by Danish police records

Question 3

give the findings from Crow’s research (1972)

Answer 3

found adopted children whose biological mother had a criminal record had a 50% risk o having a criminal record by 18 whereas adopted children whose biological mother did not have a criminal record only had a 5% risk

Question 4

give the procedure and number of participants in Tiihonen’s research to find the candidate genes associated with offending behaviour

Answer 4

genetic analysis of almost 8oo Finnish offenders suggesting that 2 genes are associated with violent crime

Question 5

what are the 2 candidate genes associated with the development of offending behaviour

Answer 5

MAOA

CDH13

Question 6

what is the role of the MAOA gene

Answer 6

regulates serotonin in the brain an has been linked to aggressive behaviour

Question 7

what is the role of the CDH13

Answer 7

this is linked to substance abuse and ADHD

Question 8

according to the diathesis stress model explain offending behaviour

Answer 8

offending behaviour is caused by a combination of genetic predisposition (diathesis) and a biological or psychological trigger (stress)

Question 9

give an example of a trigger that can cause offending behaviour

Answer 9

being raised in a dysfunctional family
having criminal role models

Question 10

what % of violent crimes in Finland is linked to the MAOA and CDH13 genotypes

Answer 10

5 - 10%

Question 11

give the number of participants, findings and conclusions or Medick et al’s study

Answer 11

Did a study of 13000 adoptees

found that when neither biological parent had convictions - 13.5% of adoptees did

20% when 1 biological parent had a conviction (so mum or dad)

24.5% when both biological parents had a conviction

this suggests that genetics do play a part in offending the environmental influence cannot be ignored - support for the diathesis stress model