We have a DS age 11 who wears boxers to bed.
His boxers have been mysteriously disappearing until I found them in a black bin bag.
Now I had spoken to him when they had started to vanish and he just shrugged it off with I don't know !
So I'm thinking his hit that part of puberty and have asked my partner to speak to him ( more of the fact his trying to hide it) he seems to think his too young right now for this to be happening ( maybe in slight denial that his lil boy is growing up !)