@Takoneko you've probably come across Gabor Mate, but for anyone who hasn't her really summarises that link well -excerpt from one of his interviews re his work as a doctor treating patients with addiction issues in Vancouver
In the downtown east side, which is Vancouver's drug area, and not only is it Vancouver's drug area, it's also known as North America's most concentrated area of drug use. We have more people there using, injecting substances than any other place in North America in a few square block radius. I can tell you that over a twelve year period, I didn't meet a single female patient who had not been sexually abused as a child; not a single male patient who had not been either physically abused or sexually abused or neglected or abandoned in significant ways.
"In North America, we like to think of addiction as either a choice that people make. If they make that choice then you punish them for it, so we build jails where we keep people who use drugs, or we see it as a brain disease that's genetically inherited. What actually happens is when people are traumatized, that increases their risk of addiction. When it comes to addiction then, what we're looking at is the impact of childhood trauma. Why? Because number one, let's define an addiction. An addiction is any behavior, substance related or not, that an individual pursues because they find pleasure, relief, or they crave it temporarily so they pursue it for the pleasure and the relief despite negative consequences and they don't give it up in the face of negative consequences. I said any behavior, so that could be sex, gambling, eating, shopping, work, relationships, or substances.