THC levels in cannabis have soared in recent years, raising the risk of psychosis—especially in young, frequent users. Studies reveal a strong connection between cannabis-induced psychosis and schizophrenia, making early cessation and treatment essential.
Given that, as a species, we have only just recently figured out how to diagnose any of these things, it is highly unlikely that these conditions are nowhere in your family lineage. There is always the possibility of de novo mutations that can shake things up, but people with schizophrenia used to just be called generically insane…or they were prophets or cult leaders if they rolled high on Charisma.