I discovered my fascination for nappies and plastic pants around 4yo. I found a pair of plastic pants at a friends house, and snuck them on. I remember going i to town with my dad to a barber shop for a haircut. After my turn, dad sent me outside to sit whilst he had his done. So I sat, and surreptitiously played with the plastic pants through my shorts leg holes. All the while trying to hide what I was doing from dad. Even then, I knew that wearing plastic pants was wrong.
Well, we got home, and shortly after, I was sprung. Dad flipped his shit, and i spent the next hour under a cold shower wearing nothing but those plastic pants. Mum eventually saved me.
Because of my bowel IC issues, Id be randomly punished by being placed in a nappy, often nappied in front of family and/or relatives. Every time Id run away happy. I think I even cheekily asked for plastic pants at one stage too!
Later, mum was told by a doctor to put me back into nappies, which she did for a day or so, but stopped - too time consuming washing nappies. I'd have no doubt that if it was in todays age, Id have been in disposables permanently.
Whilst I was in uni, I lived at home. I bought baby disposables, started using those to both get off, and to keep clean. I still had bowel IC issues, but that was slowly clearing away. I left the packet underneath my desk, out of sight of any prying eyes. Alas, at the same time, I was also deep in Transgender issues, so my mum would goni to my room and hunt down my girl clothes. Of course she found my nappies.
She would confiscate my girl clothes, but let me know my nappies were safe in their hidey hole. She never threw them away. I presumed that she was tacitly ok with them, so long as i was buying them and managing my IC issue, and she didnt have to deal with dirty pants in the wash.
Ill never get to have kids, so Ill never get to deal with the issue of pre-teen/teens seeking nappies for thrill or comfort or need. If I did, Id be like some of the others here, Id question them, cauthion, but otherwise support them in whatever they decided.