Just because I am up in the middle of the night, I will give a somewhat generic answer to this, others can probably respond with more knowledge than I.
I don't know that we have heard anything about drugs in the family tree but as far as their neck of the woods, it is Houston, a huge city in Texas, over 2 million people, in a state that borders Mexico (which may have had something to do with DV's "Hispanic" kidnapper tale). In a quick web search I see it has been named the 4th largest, 5th and 6th depending on the year, city in the U.S. I am sure one can access any drug they want here unfortunately. Of course that is probably true almost anywhere in that "where there is a will, there is a way" (and likely a dealer).
That being said, I don't know that drugs play into this case in any way. Others may have a better idea on that than I do. I would think if DV was into drugs heavily, he would be going through withdrawal in jail and they would be well aware of it.
Just trying to give you an idea of the city and area. I think we have some Texas residents posting on this thread who can probably give more personalized info than I.
The size of the city though would indicate one could likely find any type here. Poor, middle class, affluent. Drug crazed, sober. All races. College educated, high school drop outs. The city is probably bigger in population than some small countries.
Jmo, population and rank based on web search.