They won't do anything themselves at all? Like, get food, go to the toilet (will they pee themselves?) or even do fun things and watch tv?
Do you have any mods in your game, and have you tired repairing your game?
No mods in game. I find this is a problem with one family so far. The parents will self-care, but the teens and children will not. Thanks!
Hm, please try repairing your game
Open your Origin client and go to My Game Library, right-click The Sims 4 and choose Repair.
Okay, but does it get as far as they will pee themselves if you don't tell them to go?