I’ve gotten changed in many a Sailing Club changing rooms, TBH most folk cover up no matter what age.
On occasion you see kids nekkid on the beach then in the showers but they’re no older than ohhh…3
I’d say, if you want my opinion (and I’ve no kids either) cover up from now on. I guess you will be teaching them from now on its not excepted. Once they become 14 you can then explain deeper into the various ways society deals with nudity in both social and home situations.
Then when they go to Uni they’ll see all sorts, certainly I did 😆