To add to what Dr. Yaruss said, I think that though we know that stuttering definitely has a genetic component, how it's manifested (the epigenetic aspects or how those genes are expressed) is not a clean outcome that you can predict (like eye color, for example). So, I wouldn't say that your kids will stutter. They may, but they may not. We don't yet know enough about how genes are inherited or expressed to be able to predict that probability.