They don’t. Seriously. No matter what you read on a forum or heard from your Aunt, vaccinations do not cause Autism.
I have heard parents blame Autism on vaccines and metals and pollution and blah-blah-blah. I have known parents of Autistic children who had their children’s teeth with metal fillings pulled. Some parents put their Autistic children in hyperbaric chambers. Autistic children have been given blood transfusions. Parents have eliminated colors and gluten and meat from their Autistic children’s diets. I have spent two decades smiling and listening to their endless pseudo-science explanations about toxins and waves and whatever. At the same time, they never afford me such courtesy. I have been told repeatedly that I poison my children by having them immunized. All of those other parents still have Autistic children and I still have four neurotypical children and one Autistic child.
I’m done ignoring people who refuse to vaccinate. When only the people who are physically unable to vaccinate are unprotected, herd immunity acts as a fairly decent safety net. As more and more parents opt out because of something they heard or read or had a feeling about, that net falls to shreds. Without herd immunity, infants who are too young for vaccinations, the elderly and the immunocompromised are at risk. You know who else is at risk? Everyone.
Diseases that were nearly eradicated are returning because people aren’t vaccinating their children. Have you ever seen a polio patient who can’t survive outside their iron lung or one who is physically disabled and in constant pain? I have. Have you looked at all the ancient tiny gravestones with statues of lambs in your family cemetery? I have. Do you think our ancestors would vaccinate their surviving children to save them? I do.
Even if I believed that vaccines cause Autism (they don’t), I would never risk serious illness or death to change my child. Why are you more afraid of a disabled child than a dead child? Yes, I know it’s frustrating when your child has all of Apollo 13 memorized, but doesn’t know the months of the year. The years of tantrums, crawling under mattresses and screaming whenever a store uses their loudspeaker are exhausting for everyone. There is no joy in your child reading all of the Lord of the Rings books in one week but taking four hours to do one math worksheet.
Here’s a hard truth. All children are going to do things that are frustrating and exhausting. No child is going to be exactly what you dreamed of when you were expecting. This is not something that is limited to children with a diagnosis. Why are you willing to risk serious and preventable diseases to your child and others to avoid having a child who is different?
Do you know what you are going to someday realize? The dream you should have for your children is that they become who and what THEY want to be. Do you know the simplest thing you can do to make that happen? Vaccinate your children.