Schizophrenia has genetic associations as do some other forms of mental illness, ie..manic/depressive or bipolar illness. It is unfortunate that these folks don't take their meds...but often they take them, feel better and decide they don't need them and stop or they ditch them for the side effects or because they can't afford them. Do not argue with these people or respond to their delusional statements, just nod and stay calm. If they don't leave, call the police for help. These folks live in a reality only they can see, it's all their illness allows. I can't think of anything quite so terrifying really. Never try and rationalize with these folks along the lines of their delusions in an attempt to show them how ridiculous they are behaving..it doesn't work and they almost always have answers. In my psych rotation there was a medical student who decided to ignore this advice when speaking with a patient who insisted he was Jesus Christ. He asked the patient, if he was truly Jesus, how he preformed his miracles. The patient very politely replied that he "never talked shop" and promptly continued to talk in his delusion fashion about other things!. I ducked under the table to hide my laughter and the psychiatrist actually had to leave the room to finish laughing in the hall. The sad reality is there a fewer and fewer resources to help these poeple, particularly inpatient ones because most of these folks don't have any insurance and can't pay. Psych beds are almost impossible to get and so the patient can be kept in a ER for hours to DAYS or in critical care units for suicide attempts and we all end up paying even more than if proper psych units were maintained. Psychotics do not choose to have their illnesses anymore than someone with diabetes does, but many people don't understand this.