There is definitely some extreme paranoia and anxiety on this thread, but tbf that's probably fairly reflective of society overall. Some of my examples are probably equally batshit but make absolute sense to me...others I think are/were probably fairly sensible. DC now 21/15/12.
No fizzy drinks till age 10 (though DS3 probably sneaked in a few earlier than that age, third child etc etc...)
No phones until age 11
No electronic noise of any kind (including TV/radio/music) in the mornings before school, ever - we're so much calmer without people trying to talk over radio noise or getting distracted by screens
No screens at the dinner table
Phones in a different room and switched to silent whilst homework is completed
No TVs/games consoles upstairs (for anyone - DH and I included)
DC's phones left charging downstairs overnight until GCSEs are done. (After that, phones can be taken upstairs overnight....I think it's important that older teen DC try and learn to self-regulate before going to university...no-one's going to tell them to leave their phone downstairs once in halls)
No pyjama days, or dressing gowns/slippers to be worn for extensive periods during the day, unless genuinely ill (v bad for mental health to stay in pyjamas etc all day imo)
Encouraged to get out of the house at least once a day during holiday times, even if for just a quick walk around the block (again, I think it's bad for mental health to stay in the house all day)
I would also say absolutely no ear piercing till 11 but in all honesty that's never been a rule I've had to enforce - all mine are boys and none of their friends have ear piercings so it's simply never been an issue as they've never asked. I suspect this would have been a more difficult situation if I'd had a DD, though.