I have had symptoms since i was 5 years old, and current throughout my life. I have been on medications dicne the age of 12 and every couple years go off my meds. For me it was very hard. The difference between schizophrenia and schizo affective is... Schizoaffective it is a mood disorder with parts of schizophrenia. For example I have rapid-cycling bipolar, and schizo affective, meaning in lamest terms I have mood swings every 20 mintues, to an hour, and also delsuions, such as paranoia, hallucentions, hearing voices (in my head). Schizophrenia tends to be delsuions, hallucentaions, and paranioa without the mood disorder. Schizoaffective is less common than either disorder.
I have never once heard of drug induced schizoaffective, I have heard of drugs bringing on the disorder, but only if you have the genetics for it. As for children, sometimes these things skip generations, but bipolar or mood disorders have a more frequent occurence. My dad is schizoaffective, and 1/2 the people in my family are bipolar, along with aunts and uncles. Good luck,