What causes schizophrenia and bi-polar? I know a lot of it has to do with genetics and I heard it develops in?

early adulthood. My grandma has extremely bad bi-polar and narcissism she also had slight schizophrenia that was getting bad until she was put in the psy ward of the hospital and forced to take meds. Bi-polar is pretty bad in my family. My grandma and her sister both have it, my aunt has it, my cousin was schizophrenic and had to go to a mental home. I am 21 right now and am in college am I old enough that if I was bi-polar or schizophrenic I would know by now?