Time Traveling Twins Puzzle: The Novikov Loop
Ah, you're trying to solve the Novikov Loop, eh? Good luck with that.
Apparently, you've got twins who've been time-traveling and now you need to figure out how they're still identical after visiting different timelines.
Here's a clue:
They're not identical, they're just really good at... wait, no.
Actually, it's because of the Novikov Self-Consistency Principle. Yeah, that's it.
According to this totally-not-made-up theory, any event that can happen in the universe must also happen in the Novikov timeline.
But don't worry, we're not going to make you do any actual math or anything boring. Unless you want to, in which case...