Is it know what way is autism inherited?

No. There are many types of autism presentations as well as inheritance. For some indiv there are actually identified genetic abn(pku untreated is autism), some inheritance is of genetics for abnormal enzyme function, (poor digestion of certain proteins)for many at most a vulnerability is inherited.
Not yet! Up to 20% of autism cases are accounted for by known genetic syndromes, mutations, and metabolic diseases. In comparing genes linked with autism to those of other neurological diseases more than 1/2 of known "autism genes" are implicated in the other disorders-suggesting other neuro disorders sharing same molecular mechanisms as autism.