They can come from anywhere.

When I was a kid, we had this cat. (Not this cat, this cat is Mr. Donut.) I’d tell you her name except that it might compromise several of my passwords so let’s just call her Kitty. Kitty came from the shelter on an impulse of my dad’s, as I remember it, and was brought home on the bus. She had a lot of problems throughout her life, including it being the seventies when shelter spaying wasn’t common, so…