- There are many ways to see if criminality has a biological basis.
- We can compare the family trees of criminals and non-criminals -- If many criminal's relatives are also criminals, there might be a biological link. Fewer criminal relatives, the weaker the link.
- Twin Studies -- Monozygotic twins share the exact same genes. Christiansen (1977) found that from 3586 pairs of twins, if an identical twin was a criminal 52% of the time the other twin was…