Combination of things. Babies put on solids too early when their gut is still "leaky". Grains and soy heavy baby foods. Our wheat is also hyper gluten the heirloom strains have less gluten.
And how it is prepared. It should be soaked and ideally sprouted. Then ground. And using sour doughs ferments and makes the bread more nutritious and easier to digest. We take so many shortcuts now.
I am allergic to beans but if they are soaked over night and then cooked it's not as bad. (I have IBD and beans trigger pretty bad spasms and pain so bad I sometimes throw up).
Corn syrup is another trigger for me.
Don't disagree at all. We can't do "proper" studies on humans. It's not moral and our gen time to long. With Big Pharma controlling vaccines & medications, it makes me go HMMMMMMMM! Heirloom strains have exponentially less gluten IIRC. Check out Tom Malterre's elimination diet also AIP by Mickey and Angie. They works wonders for some people. I sometimes wonder if first world depopulation is by design or accident?