Re: Genetically predisposed, afraid of suddenly developing this illness..
Well, first off you could see a pdoc or a therapist to deal with anxiety before it becomes a real problem in your life. Identify what makes you anxious, write down your thoughts, develop some coping methods, for example I listen to music to deal with small amounts of anxiety.
I think the best way to avoid getting full blown schizophrenia is to keep going on with your life with a positive outlook on most things. I'm not a doctor, but I do have a minor in psychology and happier people tend to be less likely to get sick.
Don't fret about it, don't dwell on this fact, because by doing that you'd only be giving yourself another thing to worry about and who wants that.
But for sure I would suggest going to see a pdoc. They can give you professional information and opinions on your situation. And if needed get a second opinion, nothing wrong with that.