How would you handle your child bringing up the subject on their own? For example, he/she might come home from school one day and say, "Weirdest thing I saw....this other kid stooped down to tie a shoelace and I saw the top of a diaper showing above his pants. Really strange, eh?" How would you handle that? Just pretty much blow it away, "Yeah, that was...umm...interesting"? Or, would you feel comfortable enough to then take a little time and explain a few basic facts about infantilism and why the other kid might have been wearing? Not infantilism from A to Z, but a brief discussion in hopes of helping your son/daughter to at least be understanding of other people who are part of the community.
I had a similar experience myself early in this year. I picked up my son at work one day and he started telling me about these two teens in the store, and that one had a urine smell that pretty much followed him around. His pants weren't wet, so my son was thinking *wet diaper* and couldn't understand why a teen would be wearing one. In that instance, I took some time while we rode home to give a brief explanation of why some people do wear diapers even though beyond toddler age. I spoke from both the medical and psychological standpoint. Tried to give him just enough info so he'd be understanding if he ever came across any ABs or DLs in his lifetime. Didn't allude to myself in any way being one, but only discussed the experience he had at the store to encourage him to be tolerant of others. After our discussion, he seemed to be more understanding as to why the customer could have been wearing and didn't react in any negative way, so I felt I had accomplished my goal in talking with him.