I took it as a warning about potential misinterpretation of causes and effects, and in particular the difficulty to assign a single cause to the near absence of allergy in a population.
Allergies are a subject I need to know a lot more about, so sadly at this point I don't have an explanation for anything.
Having some babies get hit at early age by allergies doesn't exclude any other mechanism running in parallel, including other babies adapting their immune system, or even families moving out of the country for health reason.
I don't see how any of what I said is either insistant or limiting to a single cause.
Allergies are a subject I need to know a lot more about, so sadly at this point I don't have an explanation for anything.