Hello Stephanie,
I understand that you're concerned however I would not obsess about this if I were you. I would read all you can on this web site about schizophrenia to be informed about how this illness takes its toll on your mother and brother and what the symptoms are and things like that. I feel your mother should be open to talking to you about her experiences living with schizophrenia.
Like with any illness, and especially with schizophrenia, the earlier someone gets treatment with medication and therapy, the better the outcome is.
It is possible you will not inherit the schizophrenia so I would instead focus on living your life and being active in the world. If you are in high school I recommend you do volunteer work or maybe even get a part-time job.
If you are a young adult, I also recommend you do things other young people would do. The best defense against schizophrenia is to have daily interactions with other people and to live a healthy life that includes work, school, friendships and possibly relationships, all things that people have and do as a matter of course.
It sounds like you are young. Be hopeful: schizophrenia is not a dead-end. People diagnosed with schizophrenia can and often do have full, productive lives. I was diagnosed with schizophrenia when I was 22 and I currently have a Masters degree and two jobs and a third job on the side.
That is why I recommend being active in the world as the best defense against the symptoms.
Like I said though it is possible you won't develop schizophrenia. Not everyone with a relative who has this illness will develop it themselves. It is possible you won't develop it.
So be hopeful and get involved in the life around you.
Cheers,
Christina