Parental age and greater awareness is statistically accounted for in the analysis of autism rates; published reviews and met-reviews consistently report parental age + greater awareness accounts for about 20% (on the high end).
Severe autism, whether with mental retardation or not, is most assuredly increasing, and dramatically. This is worldwide, affecting industrialized countries more. South Korea and Japan are the hardest hit.
So I asked three AI programs (Grok, ChatGPT, Gemini) the same set of questions (the typical where, when, why and how type questions). They all came back with this:
Chemical pollutants, especially those that can cause germline mutations, were most common during the late 1960s to the early 1980s. South Korea and Japan were late to the game on cleaning up these pollutants; the United States started getting rid of them starting in the first Reagan administration.
So one generation after heavy pollution would be around 1995, which is when autism rates started to take off. Now that you two generations there are four people (grandparents) who can pass on mutations, so you’ve doubled your chances.
This is just AI’s opinion of the subject and shouldn’t be taken as gospel. Otherwise I would be going to Sweden to pick up my Nobel Prize.
But...we absolutely did not have so many autistic kids when I was growing up. You can’t miss the symptoms once you’ve worked with these kids (I have worked in my church’s special needs ministry). Nowadays autistic kids are everywhere and it looks nothing like intellectual delay due to Down’s Syndrome or perinatal asphyxia or the like. Doctors and psychologists in the past were not likely to all be making the same misdiagnosis.
Interesting tidbit. I did not know that.