Okay, this may sound quite stupid, but I am currently learning special relativity in my physics class (2301 OSU). So since both frames assume that their frame is stationary and that time in all other frames is dilated. So if Twin A stays on earth and Twin B travels at constant velocity to another planet, both can say that the other person is aging slower. But since the twin that’s traveling goes through some sort of acceleration to return back to earth, they do age slower (due to effects of general relativity according to my friend). But what if that twin could return to compare clocks without having to accelerate (I know its not possible but its just a what if situation), how would their clocks compare?