Genetic Factors

Question 1

AO1

Twins - Coccaro and Miles and Carrey
MAOA
XYY - Jacobs

Answer 1

MZ twins share all genes, DZ share 50%
Coccaro found nearly 50% of variance in agg could be attributed to genetics
M&C - meta analysis - 24 adoption studies - genetic influence could account for as much as 50% - env had an impact that lessened as time went on

MAOA - regulates serotonin - low levels led to low serotonin which leads to impulsivity and aggression
1980s Dutch family - males involved with rape and arson - had v low levels of MAOA

XYY - Jacobs - XYY syndrome in inmates was 3% when it is 0.1% of average population - males also less intelligent and higher levels of testosterone

Question 2

Genetic factors AO2

Witten
Walters
Caspi et al
Determinist 
RWA

Answer 2

Witten - no link between XYY and agg but lower int so more likely to be caught - explaining high prison pop

Walters - low to moderate correlation between heritability and crime using more recent studies

Caspi - link between MAOA and agg only if mistreated as a child - otherwise no relationship

Determinist - “agg gene” removes motivation to look for potential cures, and unethical as may label some “threatening”

BIo reductionist BUT means we can look for specific cures or potentially genetic engineering