60k kids have avoided peanut allergies due to 2015 advice, study finds

A lot of science supports the idea that helicopter hyper-parenting is hurting kids by having them grow up in an environment that’s too sterile. Let your kids go outside and roll around in the mud a bit. God forbid they lick the floor. Science says it’s good for them!

The Hygiene Hypothesis, which is what you have described, fell out of favor in research circles during the late 2000s. What seems to be causing the allergy and autoimmunity epidemic is a loss of keystone species in the gut that have co-evolved with humans and provided essential services to the immune system, as well as stability to the entire ecosystem. See e.g. a famous review on this issue [1]. Other important factors might include novel protein antigens and small molecules we have not co-evolved with.

[1] Darwinian medicine and the ‘hygiene’ or ‘old friends’ hypothesis. https://pmc.ncbi.nlm.nih.gov/articles/PMC2841838

1. Early-life exposure to diverse, nonpathogenic microbes is linked to lower risk of allergies and asthma: "farm effect" (Amish vs. Hutterite study showing microbe-rich house dust associates with protection). 2. What matters is exposure to the right environmental and commensal microbes, not skipping handwashing or basic hygiene. Microbial diversity is good; pathogen exposure is not.