Primates other than humans have been studied when there is voluntary alcohol consumption, and the proportions of non-human primates that:
1. develop alcoholism
2. get drunk occasionally but are generally sensible
3. always drink in moderation
4. choose to be teetotal
have been found to be approximately the same proportions that are observed in humans.
Much of our predisposition towards level of personal control, and risk taking, seems to be genetic. Upbringing may play a part, but it would seem to be a function of brain structure. In life there is usually a trade-off between risk and potential reward; it makes sense for some members of a population to be more adventurous, and for some to be more risk-averse.
I'd like to share with you two things relating to risk that I find interesting:
1. Drivers tend to drive to a level of risk that [at least partially] compensates for any safety measure. For example, if you wear a seatbelt you drive slightly more recklessly and therefore you are more likely to kill someone else (protection afforded to you still far outweighs the extra risk to others - it is mainly pedestrians and cyclists that bear the brunt of the extra risk).
This thinking is obvious if taken to extremes – imagine if there were no seatbelts and a big spike in the middle of the steering wheel... there would be a lot of very careful drivers out there!
2. The parasitic protozoa toxoplasma gondii's primary life cycle involves passing through a rat/mouse and a cat. Experiments have shown conclusively that this infection causes a rat to become less risk averse. It becomes much more likely to forage out in the open rather than skulking in the shadows, and therefore more likely to be caught by a cat and continue TG's life cycle. It may come as little surprise to some readers that toxoplasma gondii sets up residence in the amygdala. Although rats and cats are the primary life cycle hosts for TG, human infection in USA is estimated at 22.5% (much higher for cat owners!) and worldwide it is estimated at 25 - 75 % (those are some big error bars, eh?). Infection normally poses no obvious effects, very few people are struck with acute toxoplasmosis, but studies have shown effects on human risk taking and personality. People infected are more likely to be involved in traffic accidents, and less likely to accept group moral standards.
So perhaps the local crazy cat-lady has good reason...