I think it could be the result of just being confined all the time in things like tennis shoes.
When I was a kid my dad took us to some Indian touristy place. They had a plaster cast of an Indian’s foot, compared to the confined shoe wearing people of today (in the 60’s, anyway.) The Indian toes were seperated and spread much further apart than the other.
Anyway, I wear shoes only when I have to. Even in the winter, if I’m at home, I just wear 2 or 3 pairs of socks to keep my feet warm, no shoes.