Scientifically, Autism can be passed down through genetics, not as a mutation but as a mix of traits that basically rewire the brain(it can alter brain chemistry in some places, resulting in behavioral changes)
All in all, it is not a mutation, rather the result of genetic traits being passed down to offspring, altering how the brain processes information, responds to stimuli and behaves in social situations. It is not a disease and it is only bad when some poor neurotypical cannot fathom that a brain can work differently then theirs.
While we're on the topic of neurodivergency, I should clear up that you cannot "cure" Autism Spectrum Disorder, ADD, ADHD etc... Any method used to "treat" those disorders such as ABA therapy is just forcing people on the Spectrum to mask(changing one's natural habits, personality and actions in an effort to seek approval from peers, often unwillingly) all because some NT couldn't accept that a portion of the population is going to act differently.
I hope I cleared a few things up and educated some NT's