Yes, schizophrenia is genetic, but not every case has to do with genetics. If no one else in your family besides your brother has it, then it's probably not genetic, but I wouldn't risk it, anyways. Just trying a psychedelic once can trigger underlying psychiatric problems, such as depression, anxiety, schizophrenia, bipolar disorder, etc.
I'm speaking from experience. I tried a psychedelic, even though I have mild anxiety. The trip was fine, but for several months afterwards I had anxiety attacks and panic attacks and horrible anxiety. Eventually, I recovered, but I still get very anxious sometimes. Not worth it, in my opinion, and it was only anxiety, which can be calmed with supplements and therapy. Schizophrenia is a lot more complicated than that, and likely to be permanent. And you can trigger it from trying a psychedelic just once. I believe that shrooms are considered the most dangerous when it comes to triggering stuff like schizophrenia, but I'm not sure. LSD and DMT are quite risky as well. My suggestion? Stay away from the psychedelics. You can get similar visual effects with certain strong strains of weed.