Ina returns younger because she has to accelerate to get to her constant speed. Similarly, when she turns around she needs to decelerate and then accelerate in the opposite direction. This causes her clock to slow down relative to that of her twin on Earth, who doesn’t accelerate. This asymmetry results in Ina heading into Magaly’s future. If I sent both twins off in spaceships in opposite directions and brought them back together then they’d be the same age – and everyone on Earth would have aged quicker.
