It is hard to say. I am the first person in my family diagnosed with it. I was told there were psychiatric issues on my dad's side of the family and my dad's father is quite eccentric at times. I was also told that my mom's mother thought she had schizophrenia but that she was cured (not sure exactly what I believe about this but she hasn't had any known symptoms for over 30 years). I am a lot like my mom in many ways, including some of my mood swings. She is familiar with the symptoms of BP and doesn't think she has it. I have a brother and he doesn't have it. It is very hard to say where I get it from.