A handout I was given at a conference that I attended says that having one parent diagnosed as schizophrenic makes the child 18.5 times more likely to develop the trait vs someone without any family history. It also says that with a first degree relative (parent or sibling) diagnosed, the chance of a child/sibling having it is 10-12%. (In case anyone wants to know, chances with a second degree relative -grandparent, aunt, uncle- is 5-6%; two schizophrenic parents is 40%; general population is 1%
Risk increases with greater number of ill relatives or if it is present on both mother's and father's side. Maybe check out some websites:
www.nami.org
www.cmhc.com
www.aacap.org
I hope ths helps a bit. It's scary when all you can focus on is "worst case scenario". Good luck.