I don't think you're the only one, the statistics back up that most people will have a bout of diagnosable depression or anxiety at some point in their lifetime. 1 in 4 people in the US are in any given year, so that's 25% right there. People still don't talk about it openly because there's so much stigma.

I have always thought it wasn't a matter of nature vs nurture but nature AND nurture together for many things. I doubt there would be so much depression if there weren't so many dysfunctional families, just my opinion but it seems like nearly everone I know had some sort of abuse in childhood whether it was emotional, physical, sexual, etc.