If you're saying it could be the autistic behavior is learned rather than genetic, then I agree, you'd need a twin study to rule that out conclusively. However,

If you're saying it could be the autistic behavior is learned rather than genetic, then I agree, you'd need a twin study to rule that out conclusively. However, when people say "the autism epidemic is environmental" they usually mean vaccines or chemicals or something, not "learned from the parents." Despite the quantity of autism research, most of it is quite bad and not that helpful on questions like this.