What about obese smelly kids who throw their food around and howl for every waking moment of the flight.
Put children in the hold.
Saying that I sat next to two unaccompanied minors coming back from Uganda and their manners left me gobsmacked. These kids were amazing and I was lucky to sit next to them.

on one flight the kid behind me kicked my seat from Doha to Cape Town.

What about flea bites? I got my bum bitten by fleas on my Air Arabia flight!

Or a vomiter.