The paper that I cited is just one of dozens if not hundreds of studies on the heritability of the diseases. The evidence is overwhelming. Anecdotally, almost everyone I know with serious mental illness has at least one family member who does too.
The statement that 'Bipolar disorder and schizophrenia (the main causes of psychosis) are genetic, not caused by "spiritual crisis"' is not backed by the results of the paper.
There are many things you don't know and don't know you don't know, that is complicated to explain. I, for sure, am ignorant of a lot too, but at least I know that estimating heritability on the occurrence of bipolar disorder doesn't prove that these disorders are "caused" (you used this word, while the article doesn't) by genetic factors.
They don't use that word because that's what heritability implies. The fact it has a genetic cause doesn't mean that everyone with those genes will have bipolar disorder.
Of course I don't know everything. I am however more inclined to believe things with a lot of evidence (such as the genetic basis for schizophrenia and bipolar) rather than those without evidence (that it's caused by spiritual crisis).
I do believe in the facts reported by that link (although I don't blame people who don't, scientists in general are not trustworthy). I didn't say that.
