As a baby I was born with a pituitary issue which meant my hands and feet were abnormally small. They never grew that large at all. I can run and walk fine and they’re not deformed or anything, just tiny. I might have some hilarious world record for smallest hands and feet on a fully grown adult! Luckily my condition hasn’t affected any other part of my body.
Funny, I never have trouble finding size 13, but I’m more of a 12.5. They don’t sell or make them at any stores, so I can’t even try them on to test out my theory. Couple years ago, I was on Amazon looking for some Merrells, and I noticed they did have a 12.5 option available, it jacked the price up from 100 to like 250. So I guess they do make them but in very limited supply.