Personally, my Mum hates swearing in general and says she'll never allow it in her house even when my sister is an adult (she's 14, I'm 21). But I've gone round friends' houses, etc. and seen them and their parents swear around each other like it's their normal thing to do.
I don't think either mindset is wrong really, but which do you prefer? Would you "tell off" your adult child if they swore in conversation with you?