Children are getting bugged all the time.
In almost every game I had a child, they bugged themselves in front of some interactable object (mostly fridge). Then you couldnt move them, couldnt interact with them, and when you tried, the character would eat food from fridge instead of talking to the child or doing any interaction with it. If you were able to interact with the child, it would be something completely different (Click on talk with child, but for some reason they give them bandage). Then the child becomes broken. The only way to get from this debuff is alcohol (that children cannot use) or talking to the character. Since you cannot talk to them, they will be stuck forever, randomly getting ill and injured in night and you cant do anything with it. So you can just pray the game ends before anyone dies.
You can find broken toys to make toys for kids, but generaly you never need to because using the basic play actions and talking to adults (if they wont get bugged) is enough for the entire game.
Children are useless unless you teach them certain things to make. They do everything slower and get sad if they work too much (They wouldnt have time to be sad if they worked 24h shifts in mines like kids in frostpunk). Also it is interesting that you cannot teach child how to make alcohol, but you can teach them how to make 3 different types of cigarettes.