Nothing "makes" a hen go broody, she a female and decides for herself. As the father of three girls I've learned the do what they want , when they want.
That said, I have a hen sitting on two wooden eggs plus one of her own. Don't know what possessed her to go broody but she did. Iv'e...
My OP is that the wooden eggs that I use "discourage" them from egg eating. Once they hurt their beaks pecking at the fake egg they may figure all eggs are hard and will hurt their beaks. I keep the wooden eggs in the the nest 24/7.
Nest boxes should be small enough so they can't hang out and...