I'm of the opinion of others here: I cannot safely use drugs or alcohol, period. The origins, characteristics, etc., are purely academic and don't mean much, IMHO. That said, it is interesting to discuss.
In rehab they told me a few things that stuck with me. Alcoholism is a bio-psycho-social disease, and this fact is what makes it so confounding to get one's mind around (and for society to do the same, and makes it easy to bring morality and ethics into the debate, as far as society at large is concerned), in my view. There are many moving parts, so to speak.
Separately, I went to rehab on Long Island, which happens to be very close to Brookhaven National Laboratory, where they are doign some ground-breaking work in terms of studying the genetic, as well as physiological and neurological components of addiction. The scientist who came to speak to our group of 85 one day said that their lab had traced the disease down to a misfiring neuron in the brain. More specifically, the brain's P300 neuron misfires in addicts/alcoholics and this causes a predisposition to becoming an active addict/alcoholic. But is does not predetermine one's alcoholic fate, it is merely more likely that one will develop an active addiction if one has this misfiring neuron. That and $3.75 will get me a cup of coffee at Starbucks, but maybe someone found it interesting.