Interesting question by empty life, worth thinking about. I find that internal factors can be dominant but that if good things come into your life your thoughts become less aggressive, more cheerful and you will get more confidence. So yes I would say that depression will always be prominent but can ease up when good things/people come into your life.
Just as you I have a distant, cold, manipulative family. Ironically the stigma attached to depression and the absence of not having a job as a result of it can make you even more isolated. The people I do tend to attract are horrible to get along with and just use me because they think; 'she doesn't have anything/anyone I can just exploit that.' One guy just even said so to my face; 'but a normal person would not get involved with a girl like you, so what do you expect: Mr. Nice Guy?' In between those two groups you'll find some gentle people but they're so busy with their families that, although I value their friendship, I do not get to see them often. Bitter loneliness is a result of this situation and, although I try very hard, I find I can only do little to change that.
I used to believe in this whole 'you make your own happiness concept' that the world embraces (and which so many psychologists try to force down your throat), but I only partly believe in it now. True if you don't go out or do anything your situation won't change. But happiness is for a large part also based on just sheer luck of being born into the right family, be gifted with a normal brain and the right genes, things you simply cannot influence. And judging by most posts in this forum; we were not the group of people who were that lucky.
I keep trying to be positive, but with a genetic and chronic predisposition to depression and other mental illnesses I find that it's taking all my energy to hang on to this thing I'm just not very good at - it's called life.