Thinking and reading about the twin paradox recently, I encounter a lot of explanations and resolutions that don't make sense to me. At its most basic, the issue is- when two bodies are in different frames of reference, why shouldn't relativistic effects affect both equally, negating time dilation, length contraction, etc for one inertial frame compared to the other? (Note that as usually formulated, the twin paradox includes the round trip. But if a round trip is required, that implies no relativistic effects on the outgoing trip, which is not the case.) That said, the resolution of the 'paradox' is solely that the origin and destination are in the same inertial frame. If desired, I will elaborate. Has this never been posited? It seems the only solution. I think asking a related but different question sheds a little light on this- Imagine each twin boards a ship and travels in opposite directions at identical speeds to equidistant destinations. (Imagine a return trip if you want.) The relativistic effects on each will be equal and the twins remain the same age, though they age less than someone remaining at their origin.