I think it's an epigenetic issue with some and an issue with people being raised by bad parents in a bad environment. People who have a strong, healthy upbringing in a good environment don't end up with mental illnesses unless it's something genetic or a serious trauma takes place.

We've witnessed a couple of generations where the family has been dismantled and where kids grow up in high-stress environments. The increase in mental illnesses is symptomatic of that and it's not something that psychotropic medications will ever fix.