Hey caz , heres my bit to add on,not medical as such as previous peoples early experiences, ive written all about my kink in other places, but here goes.... i was living in a house which we moved out of when i was 5, so it happened around then....i must have been constipated, mother called me inside, she whipped my shorts and underwear down and hoisted me over her lap, i then got a vaselined finger pushed right up my bum, followed quickly by a ball of household soap, i recall crying and struggling at the time, then i was dressed and sent outside again.
The soap began to sting/burn , and i didnt want it in me, so i sat on the toilet and pushed , eventually it plopped into the bowl, but nothing else, things must have cleared though, as it never happened again, and im here almost 60 years later to tell the tale.
I do know this led to my fingering my bum hole even before i got errections, and i know it felt good, and the odd bit of soap found its way there , self inserted.
Some friend of mothers used to call now and then, leaving a pile of womens mags for her to read, i also used to look through them, as some has ads for stockings and corsets etc, now one had an ad for suppositories........didnt have a clue what they were , so dictionairy out and found what they were, by now i was considered old enough to go on the bus to nearby town, where i bought some.
Lots of fun was had ! another time i had another make of supps said they could replace enemas....dictionairy out again........so i gave myself my first enema via an empty washing up liquid bottle.....
So i now have a serious bum fettish, which involves my bum or someone elses i love being given soap, suppositories and enemas etc, prostate massage, diapers and anything else bum related.
So all my kinks originate from that one time experience, and have also morphed into other things, my kinks are now catered for by my partner caz, though i miss giving enemas etc as she doesnt like them, but i will continue to work on that.......
Most of this is posted elsewhere, but ive added it again here in response to initial question.