Would you prefer your children to not swear; and if yes, why?

I'm almost sure this is mainly a status thing. Frequent swearing is perceived as crass, a lower-class practice, and so aspirational parents encourage their children not to. This intent then proceeds to backfire when children develop their own social networks: status relations among children and young teenagers are quite different from adult ones, and swearing in this context is often a marker of independence and perceived maturity. This gradually unwinds during the teenage years as swearing in the presence of adults becomes more socially acceptable and adult-style status relations start to assert themselves.

The only thing that confuses me about this model is the lack of countersignaling, but perhaps children of that age can't reliably parse signaling at that level of indirection. Or maybe I just don't remember enough childhood social dynamics.