Of course, the cause of autism should be investigated and no sensible person would suggest otherwise.  Unfortunately, a number of uninformed people have been pushing the notion, based on thoroughly discredited studies, that vaccines are the cause of autism.

As for the having few epidemics, you have, perhaps unwittingly, made the case for vaccines.  Why do you think that there are no epidemics?  The outbreak of measles in California in 2015 is an example of what can happen when insufficient people receive vaccinations.