So is there a possible correlation or causation between "helicopter parenting" -> "not letting kids play in the dirt" -> "weak microbiome" -> "autism" / developmental difficulties?
Definitely could be other factors too, like non-diverse diets.
Definitely could be other factors too, like non-diverse diets.
And it is further true that in social situations the anxiety level of the autistic child increases, as does the parent, and so people viewing the situation might be biased to see a highly anxious parent with a spoiled kid, and assume the causation.
My kid loves playing in dirt, he also loves to track it into the house, no-matter how many times you tell him. We live with dirt, and autism. My kid is also a genius, so there are good things about it also.
I'd caution that there are at least two variations of this, with rather different treatment implications:
1. ("Hygiene Hypothesis") Modern immune systems are coddled degenerate weaklings that should be toughened up with exposure to survivable levels of hostile microbes.
2. ("Old Friends") Your immune system is complex and its ideal tuning is reliant on normal exposure to benign, commensal, or symbiotic microbes which help it calibrate or even serve as outsourced components.