That's not something we can really tell you. It takes a lot of family history, knowledge of genetics, etc. You'd have to see a doctor to really get into it.

A sibling of a person with autism is much more likely to be on the spectrum but the general consensus (as far as im aware) is that its considered a spontaneous mutation. But yeah, your better off asking a professional.

That depends on a lot of things. The type of autism, what gene you need to get, if it needs to be from both parents or only one, or only the mom or dad, and whether or not your boyfriend even has the gene or could be carrying it. There's so many variables that you would have to talk to a special doctor that goes through the family history with you, and tells you what the odds are. Even they can't be 100% sure but they can give you an idea.