The solution to the twin paradox that is usually given is that the twin traveling away from the earth is not in an intertial frame of refrence since he has to accelerate when returning back to the earth, but what if he doesn't.
What would happen if the topology of the universe were that of $\mathbb{T^3}$ or even of $\mathbb{S^3}$? You could then follow a geodesic trajectory throught spacetime and still return to earth without having undergone any acceleration.
>Inb4 expanding universe
This entire argument is theoretical since I don't actually belive the universe is a 3-torus.