I'm a male who's almost 30. In the last few days, I found out that 9(?) members of my family have experienced hallucinations and/or delusions. They're all highly functional, have never been medicated, treated, or diagnosed for schizophrenia. Apart from them telling me they've had these symptoms, I wouldn't have suspected schiz*-associated impairments. That is, they seem normal (after accounting for autism, bipolar, etc.)

As far as I can remember, I've never had delusions or hallucinations, except some due to a sleep disorder (confusional arousal).

I had a brain MRI a few years ago for a different reason. Out of curiosity, I looked at my images. This is what I found:

... EDIT: I can't post a link, because I'm new. But, it's on imgur as zTCpz3Z.jpg

... Clearly enlarged ventricles.

So, what does that mean for me? I spent perhaps hours looking for information on enlarged ventricles, and how that relates to likelihood of onset and psychosis. I wasn't able to find that info. I did find this: supposedly, new-onset schizophrenics and "ultra-high risk" patients have near-normal ventricles. Mine are clearly abnormal, and yet I'm free of hallucinations, etc.

I do however experience anhedonia, chronic derealization, and some other associated symptoms. I'd never be diagnosed on this basis though, because I have comorbid autism; so, the DSM-5 would require delusions and/or hallucinations (as I recall). Also note: obviously, I'm not medicated.

... In short, why am I not experiencing debilitating impairment or any psychosis? And is it almost certain that I will, given my MRI?