[jkukul]

There was a very interesting discussion recently on this topic. [1]

There are various hypothesis:

* changes to gut microbiome composition due to modern diets and overuse of antibiotics

* excessive cleanliness and hygiene. The "hygiene hypothesis" suggests that lack of exposure to diverse microbes leads to improperly trained immune systems

* increased exposure to chemicals, plastics, and pollutants that may disrupt immune function

* Cesarean sections and formula feeding rather than vaginal birth and breastfeeding

[1]: https://news.ycombinator.com/item?id=37195905

[pbnjeh]

Exposure to cigarette smoke was also considered a candidate or reason, when I was younger. I haven't kept up with the thinking on or about this, but I believe it's still considered valid.

Remember, a few decades ago, a lot of the "Western" world smoked, including in public spaces and around kids. As I understand it, a lot of the rest of the world has caught up and still does so. And the Western world isn't exactly rid of the behavior, either.

P.S. I wonder whether anyone's studied possible multiple-generation, genetically-communicated knock-on effects of this.

P.P.S. "Pollen" is also a Racket language based blogging and authoring tool or environment. A bit sorry to see the name become overloaded.