AW,great question.
Some people say it don`t matter why we are this way,I believe it does.Several reasons come to mind
the more we learn ,the better we can become at prevention efforts with our youth today.
the more we learn,the better rehabilitation can become.
If you read the article at this link,it may shed some light on your question.I find it very informative and I plan on doing futher study on it.
William E. Swegan, 2. The Psychology of Alcoholism