Bio Exp- Genetic Flashcards
Assumptions Genetic explanation for offending
Criminal tendencies can be inherited
Investigation of a persons genetic material, brain or body will reveal criminal tendencies
Stressors in the environment can trigger genetics but people are predisposed to crime (diatheisis stress model)
Twin studies
Christiansen 1977
Over 3500 twin pairs in Denmark born between 1880 and 1990 with ‘offender behaviour’ checked against Danish police
Found:
Concordance rate:
35% monozygotic
13% dizygotic
Shows not just behaviour inherited but genetic predisposition aswell
Candidate gene MAOA
MAOA:
Gene coding for enzyme that regulates dopamine and serotonin which has role in impulsive aggression
MAOA-L (variation causing low activity this enzyme)
Chambers- Called warrior gene- found more in New Zealand Māori men 56% vs 34% white men
Mutation of X chromosome so affects men mostly because …
Brunner- 28 men from large Dutch crime family involved in repeated impulsive crime. Found had MAOA-L variant
Candidate gene CDH13
Linked to substance abuse and ADHD
5-10% of severe violent crime in Finland is attributable to MAOA and CDH13
Diathesis stress model
MAOA- Frazzetto
Found higher levels of antisocial aggression and MAOA-L variant in men but only those who had experienced significant trauma before age 15(physical or sexual abuse).
Those with variant but no trauma didn’t show same levels of aggression
Twins- Mednick
-13.5% turned out criminals if niether biological or adopted parents where criminals
-20% if bio parent was
-24% if bio+adopted were
Shows both affect child through nature and nurture but biological apears to have biggest impact with 7% increase
Strength genetic (applications)
can Intervene with children in families with these genes- CBT, anger management, can try and prevent them becoming criminals
Strength genetic (hollistic)
Diatheisis stress acknowledges both bio and environment, better then atavism, more hollistic
Limitation genetic (issues with study)
Issues with twin studies:
Identical twins may be treated more similar than dz twins, (as well as more similar genes)
This may affect behaviour being more similar
Adoptions may take place at later age but child may already have experienced crime by then
Adoption study
Crowe:
Adoptees who’s biological mother is criminal has 50% chance of criminal record by 18
Vs control of 5%