i listened to some guy on dennis miller's show whose kid had depression.
from what his kid went through, it seems very real.
but there's a difference between being depressed because you're ugly, don't get laid, broke, etc. and having clinical depression (wanting to kill yourself because you fail at some simple tasks, etc.)
Yes. Some people are basically born with difficient brain chemistry. This cannot be underestimated, as it differs greatly from simply being down about something that has actually happened in your life.
Some people have great lives, but have always been depressed, and don't know why, and can't imagine ever getting better, because there is no external reason. That is when it's scary.