> If Tylenol causes autism, how did those parents in the 1920s get their hands on it?

The claim is that Tylenol is a factor that increases the risk of autism. It is not the cause of 100% of all cases.

That said, the first synthesis of Paracetamol in the USA was Johns Hopkins in 1877, so maybe the answer is they went to Baltimore.

Now do Tylenol sales kicking up in the 60s.