A couple of studies - of alcohol and prisons - suggest criminality is to a large extent due to the obvious factors of poverty, mental illness and alcohol.
A report from the Australian Institute of Criminology reveals that nearly half the homicides in Australia involved alcohol. Homicides that:
- happened on weekends or evenings; or
- involved male or unemployed victims; or
- involved a male killed by a female partner
all mostly involved alcohol.
Yet I suggest this study is very specific to Australia. In the USA, for example, where handguns are far more plentiful, the circumstances of homicide would likely be far more varied (homicide rates are elevated by increased opportunity - as presented by a proliferation of handguns).
And a survey of NSW prisons reveals remarkably consistent factors in incarceration, which must be a good proxy for serious criminal action.
About half of NSW's inmates were expelled from school; half were unemployed; risky drinkers; were intoxicated at the time of offence. Pretty much the usual suspects - although there was one unexpected finding: more than half had suffered a serious head injury.
The NSW prison system has been highly successful in keeping HIV at bay, with only 0.1% being HIV-positive (although five wrongly thought they were infected!) However, hepatitis B and C affecte one in four and one in three inmates respectively, signalling "iv drug use and risky sexual behaviour".
Yet only one in six inmates was aware of a sexual assault in jail last year, which was apparently an improvement on eight years ago.
The overriding impression is that poverty and lack of education (which is a direct factor in poverty) are significant indicators of criminality - which is exactly as one would expect. It's also reasonable to expect mental health issues to be significant, but the report-on-the-report is silent on that (apart from the 'head injury' finding). However, I did find mention of the previous survey (here) which, as a proxy, says 41% of male prisoners (and 54% of females) had in the past had mental health treatment or assessment.