@Jesy,
Jesy, as I said in another thread, in order to conclude that time slows down for one of the twins, you must know it is that twin that is moving. Clocks slow down with motion, that's an essential element of the Lorentz transformations.
What I find inconsistent is that Einstein and other relativists say the travelling twin will age less, all while claiming that there is no way to know who it moving.
How would that work, exactly?