The main point that Simon stressed is that the majority of heroin addicts are in pain.
I did not suffer sexual abuse when I was young, so I never responded much to the stories of those who did during my recovery, but I remember a huge portion of addicts in the NA meetings I went to had been abused. And the vast majority was bisexual, or at least had had sexual experiences with both sexes. This was not my case either and being hit on by men, as sometimes happened, took some getting used to. (I was always careful on turning them down to let them know that I did not think less of them, but was flattered instead. I just didn't "play on that team" as they say in Brazil.)
First we start out with an unusual point of view. Most addicts are in pain. This is quite surprising. It surprised me. I thought they were just in it for the euphoria.
Here is what Dr. Shavelson found in his study of 200 addicts: a high proportion of severely abused children (beatings, rapes, rapes of siblings). He questioned his study methodology. He thought there must have been a flaw in how his sample was selected or in how the questions he asked were framed.
Then while he was doing his research, an article came out in the Journal of the American Medical Association that said that the addiction rate goes up for male sexually abused children.
I remember one guy used to crack up everybody by saying, "Nine out of every ten people attending NA meetings have serious issues with their sexual identity and one is lying."
I highly recommend any addicts reading this to look at that blog article above. (There are some great links there, also.) It mentions heroin and pain. But from my experience, pain is at the root of the vast majority of addiction to hard drugs.