There is some evidence to suggest schizophrenia like other forms of illness, physical and mental, is to some extent hereditary and there are certain families plagued by this illness in successive generations. Some argue that even when not so extreme a predisposition is inherited and yet others say this predisposition can pass an entire lifetime without showing itself while in others the illness is triggered by certain conditions (sometimes/usually unknown). The bottom line is that even though this is far from being an unknown affliction, with all other mental illness it is something of a Cinderella within medical research and has not had anything like the research funding it should have to reflect the incidence. Mental illness is not as glamorous a field for researchers (or their backers) to enter as, say, cancer or IVF, etc. Discuss this with some authority in the field (best of all go to someone in research/academe if you can). You face a difficult choice - but remember, no embrio is guaranteed a burden free life.