My younger brother and sister do, but I still cringe and I'm 33.
What's wild is I don't really get on my own kids for cursing, to me it's more about the intent and meaning than the actual word. Most curse words are expressive, but often times we use them as nouns and adjectives. For example, if my 14 year old is hooping or playing a video game and a "fukk" slips out, that's no problem, however if he was to call someone a "muthafukka" that's an ass whooping and a half. My rule is don't use words to hurt or tear someone down, but feel free to express yourself.