A pet-peeve mentality exists around major foods - some people just can't handle this or that and have allergies to them. Major allergenic foods like corn, soy, and wheat tend to feature a pesticide that works by inhibiting the shikimate pathway, a process that processes amino acids, thus disrupting digestion and encouraging intruding pathogens to grow: glyphosate, brand name Roundup(1). I certainly consumed a lot of pesticides in the first 15 years of my life and sure got my doses of candy and soda with corn syrup back in the day. The dairy I was said to be allergic to in infancy was grain-fed, had artificial hormones, you name it.
Almost every autistic person is believed to have gut issues where they leak nasty things into their bloodstreams that assault - their brains(2). No matter who we are, our brains will thank us for being proactive about our guts!
Sources:
1. http://www.anh-usa.org/half-of-all-children-will-be-autistic-by-2025-warns-senior-research-scientist-at-mit/
2. https://www.scientificamerican.com/article/gut-bacteria-may-play-a-role-in-autism/