I've always found the twin studies confusing at best, while i'm no psychologist i do try my best to keep informed on the subject as I care for one of my sisters who has the condition.
The studies i have looked into seem to disregard the fact that schizophrenia can be learnt condition.
It's good that you're taking an interest in the subject. You're right that aspects of the research can can get rather confusing, though. I would recommend having a look at this lecture by John Read. I will be discussing some of his work in a future video but feel free to check this out, anyway.