The entire cast has a disease which causes them to fall over whenever they laugh for an extended period of time.
- Yeah, it's called being a pothead. Everyone on the show is a pothead, which is why they laugh at everything.
The cast were Uplifted and live on a future planet Earth. Father Christmas is the Time Lord looking after them.The characters are all anthropomorphic animals, but there are still worms, bugs, ducks and other birds. Their houses are Bigger on the Inside. The Pig family have been to Italy, so they are living on Earth of one sort or another. Conclusion: the cast's ancestors were Uplifted by scientists on a future (or replica) planet Earth. We've only seen one 'human' character - Father Christmas. He's a Time Lord hiding on the planet, supposed to be keeping a discreet eye on things, but can't help getting involved. (There are also a selection of talking potato TV stars. Probably genetically engineered celebrity vegetables.)
- Another 'human' character is The Queen. She is either a Time Lord, really the Queen, or a shapeshifting lizard.
Peppa Pig is actually in a post-apocolyptic society where the social interactions of people are reduced down to creepily simple sentences.