Genetic Factors

Genetic Factors

1. Twin and Adoption

   • A01
     • Twin studies with MZ and DZ, if MZ more alike in aggression than DZ assumes genetic link as MZ share all genes, DZ only half
     • If positive correlation between child and biological parents aggressive behaviour suggests bio.
     • If positive correlation between child and adoptive parent, assumes environment not bio
     • MILES AND CAREY- studied adoptive boys with criminal convictions. many had bio parents with criminal convictions
   • A02
     • Support...
       • MILES AND CAREY- meta analysis 24 adoption, found strong genetic and environment in younger, and strong genetic in older individuals
       • RHEE- 51 adoption, strong correlation of genetics and aggression/antisocial behavior
     • However...
       • Mostly self-report. when observattional, less correlation. so method used has effect on findings
       • May be other factors involved, eg age
       • PLOMIN- found no differnce in correlation between MZ and DZ

2. Genes

   • A01
     • MAOA- gene that regulates metabolism of seratonin. low levels = aggression. so may be due to this gene
     • BRUNNER- violent Dutch family, low levels of MAOA, faulty MAOA gene so seratonin not regulated.
     • CASPI- two variants, one with high levels of MAOA and one with low. low=more aggressive ONLY if maltreated as child. assumes environment is factor, not all genes
   • A02
     • Support...
       • YOUNG- rodents, eliminated a single gene, the mutation showed to cause aggression. can be seen in mice. Also exists in humans but its function isnt known
     • However...
       • VALID? focuses on those convicted of violence but only represents minority. also, murder is ONE violent act not constantly aggressive
       • many genes which contribute to behaviours so hard to name just one. also, may be due to SLT and environment
       • BRENNAN- genetics significant in case of petty not violent crimes

3. Violent Crimes

   • A01
     • Inherited temperment/ personality makes people more likely to commit violence. research shown clear evidence of genetics and environment as high rates of criminal violence when both bio and adoptive parents are violent
   • A02
     • HOWEVER... ethics, labelling someone as a threat based on genetics. as evidence isnt conclusive.

4. A03

   • CULTURE- !kungsan tribe
   • ANIMAL- young, generalisable?
   • SOCIALLY SENSITIVE- may cause distress talking about crimes commited or giving up child.
   • REAL LIFE- led to genentic engineering to prevent crimes.