how did you become addicted?

Hubby and I were discussing addiction tonight. Bear in mind, neither of us are addicts, but one of us has more relational experience with addiction. My husband believes that people end up addicted to heroin (just as an example) by just trying it once for fun... whereas I believe that most people usually use to cover up pain, after a surgery in which pain meds were prescribed, etc. we are both genuinely interested in personal stories of addiction progression, and how one goes from maybe casually drinking once a month with friends to having a full blown addiction to something. Id love to hear your stories, if you'd feel comfortable sharing, as it might bring light to a subject that is often viewed as "taboo" when it shouldn't be.