Is autism hereditary?

Hi,  I am wondering what peoples views are on whether autism/ASD is hereditary.  My daughter, now 18, was diagnosed age 15.  Her assessment came as a result of being an inpatient for a severe eating disorder.  6 months later my son was diagnosed at age 19.  Neither my husband or myself have been diagnosed or assessed but I can't help wondering how we managed to bring our lovely children up for 15 years without picking up on the ASD.  My daughter was always anxious but it appeared to be manageable.  Retrospectively it clearly was not manageable and she ended up very ill.

Anyhow, I was wondering if the reason that we hadn't picked up on any ASD traits is because in our house eveybody's behaviors is perfectly typical.  When we discussed how they played as children both my husband and me said to the psychologist 'but doesn't everyone play like that?'.  In the tasks that they did for the ADOS they gave responses that we thought were typical responses.  My husband has always been widely regarded as eccentric but he has been very fortunate in his employment in that everyone loves him for his eccentricity (including me).  I myself am extremely introverted and hate social situations, avoiding them at all costs unless absolutely unavoidable.  So I was wondering if the reason why both my children have ASD could be because either me or my husband (or both) unknowingly have it, and maybe that is why we haven't picked it up in our children.  That is to say in our house ASD is normal and most others walking through our front door are in effect neuro atypical!   I would appreciate your thoughts.  Thanks.