I do as well. I was never able to find out. I had him checked out at the country shelter for a microchip and had them take down his description in case someone called looking for him, and I spent months scouring lost pet ads for anyone missing a cat like him when he first showed up. That was about a month after my previous cat, Keiko, had passed away suddenly and I wanted to be
sure that I was not causing someone else that kind of pain if he had just slipped out and gotten lost or something, but no one ever came forward. It's unfortunately pretty common for people to dump cats near the barns in this area because for some reason there's a mindset around here that any cat, even one that's never been outside before, can integrate into an established population of barn cats and survive on their own just fine. For most dump cases, this sadly does not seem to hold true.

But thankfully I was at least able to get Casper inside where he's safe and comfortable before anything happened to him.
I suspect he was dumped here rather than born here as mentioned above, but we'll probably never know.