It's possible we currently can't count that high and eventually when we do we can map this stuff. Otherwise mental disorders couldn't be categorized, they would vary too much. Each afflicted person has a unique experience, yes, but they're similar enough that there likely is/are cause(s) even if factors outside genetics are a part of it.
Hmm, I'm not sure, but it seems like I might have come across as somehow being against DSM there. That really wasn't my intent. I don't think there is anything, specifically, wrong with DSM, at least, as long as people aren't treating it as somehow "gospel."
What I was agreeing with, though, was this part: "The best we can do is embrace an ecumenical four-dimensional model that includes all possible contributors to human functioning: the biological, the psychological, the social, and the spiritual. Reducing people to just one element – their brain functioning, or their psychological tendencies, or their social context, or their struggle for meaning – results in a flat, distorted image that leaves out more than it can capture."
That is, if we take a "one-dimensional" look, we are apt to miss something. And probably a lot of somethings.