Not why the addiction, but why the pain.

In the real world there is no nature vs. nurture argument, only an infinitely complex and moment-by-moment interaction between genetic and environmental effects

Medical thinking usually sees stress as highly disturbing but isolated events such as, for example, sudden unemployment, a marriage breakup, or the death of a loved one. These major events are potent sources of stress for many, but there are chronic daily stresses in people's lives that are more insidious and more harmful in their long-term biological consequences. Internally generated stresses take their toll without in any way seeming out of the ordinary.

Not why the addiction, but why the pain.

A long-term substance abuser, a few months before his death, penned this poem: Went downtown, Hastings and Main, looking for relief from the pain. All I did was find a ticket on a one-way train. ... Give me peace before I die. The track is laid out so well; we all live our private hell; just more tickets on the hell-bound train.

It is impossible to understand addiction without asking what relief the addict finds, or hopes to find, in the drug or the addictive behaviour.

We may not be responsible for the world that created our minds, but we can take responsibility for the mind with which we create our world.