Yes. I have read this paper, and saw that documentary, as well. But the fact is that the causation of schizophrenia hasn't been established. Also that genetic link can't be traced to schizophrenia, so its kind of a broken theory. And I would say it is abundantly reasonable to say that over doing it will have back lash eventually, whether or not schizophrenia be the symptom.
As far as your post goes, you are kind of poisoning the well so to speak. You proclaim that it may be entirely based on genotypes, which has no scientific basis(no causation has be proven to exist), and that most the population have the strong genes and the minority have weak genes, with the mediocre genes riding somewhere in the middle. Obviously some would take this wrong and others would make assumptions so as to justify their habits.
As well the stats that are used are created to scare people, 2X greater risk?? 2X/5X of what, to really know you would have to have a bank of all DNA and schizophrenic cases that were precipitated by drugs and other environment related issues. And the "...one or two weak genes...you get paranoid." Is that based on any real information cause I haven't been privy to such ravenous statements. That requires an entirely different set of data, which is even more detailed because any person is lying if they say they have never felt paranoid.
I posit that is the people who have an experience that isn't simply absolute bliss, they feel that they have a condition. Depression, paranoia, ect. ect. are all merely temporary states that are created as permanent. People are thinkers and our society doesn't like people to think, you hear it every where; "I wish I could just shut off my brain.", "I wish I didn't even exist.". Everyone has a need for perfection these days and instead chaos and instability are the likely routes to happiness. Come on man, this is just life. Every one gets paranoid, everyone hears a voice, and everyone has equal risk of developing schizophrenia. No matter what you can never rule your self out as that unfortunate bearer of the flapping flag.
Peace