[einhverfr]

> For instance, most of the literature I could find does agree that there is a biochemical basis for schizophrenia.

Basis != the phenomenon though. But try reading Julian Jaynes' "The Bicameral Mind" which will give you an idea into at least one possibility into how culture fits into it.

That there is a biological aspect to mental illness is beyond dispute. However that does not make it a biological phenomenon. There is probably a biological aspect to language too. That doesn't mean that language is biologically determined.