Hi chinglu.
In my post #346, for SR-only case, I removed all extraneous variables (such as Earth-sun astronomical SYSTEM dynamics/orbits) and just had the twins and their respective clocks/biologies telling (ticking off) the 'time' at their respective rates. If one twin and his clock 'took off', then his clock/biology INTERNAL PROCESSES change their rate to their new motional state 'standard' which is different to the previous COMMON STANDARD which obtained while the twins were co-moving in their 'starting standard' co-moving state. So depending on WHICH TWIN DEPARTED from that prior co-moving standard, then that twin's NEW 'standard' would apply to HIM ONLY.
This is easily seen if we later ask the stay-put twin to ALSO ACCELERATE and JOIN the first-moved-off twin.....at which point when the twins are again in their NEW co-moving COMMON STANDARD state, their clocks/biologies would AGAIN be IN SYNCH but in a NEW standard state/rate. See, neither is 'wrong' clock/biology, but rather 'merely different' from other standards. Any standard can be chosen as THE standard, but if we have BOTH twins move to a new co-moving state, then the NEW STANDARD will apply. Neither the old standard or new standard are 'wrong', they are merely different standards which can be used accordingly as the 'starting standard' in a particular experiment/analysis, that's all.
and...
In my post #758, for the GR-only case, I again removed extraneous variables
such that the sun-earth-ORBIT NUMBERS was the same for BOTH twins/clocks. ALSO the Earth-spin itself was changed
to make the SUN position in the sky a CONSTANT for BOTH twins/clocks....see?....
BOTH of these things were CONSTANTS for BOTH twins/clocks irrespective of whether they were at the top OR the bottom of your mountain. In this case the twin that moved up/down the mountain would have a different rate of clock/biology process due to Gravitational effects, but the astronomical system had NO EFFECT OR RELEVANCE to their respective clock/biology rates in the NEW position up/down that mountain. Moreover, I also pointed out that because they both could have started the experiment EITHER from the bottom (and one moved UP) OR from the top (and one moved DOWN)., and NEITHER clock/biology was 'wrong', but rather merely different from their starting position/altitude 'standard'. Again, this can be easily seen if we have the OTHER twin do the moving, and then have the other twin join him in their new co-located/co-altitude position which will have the NEW same standard for both of them (from which they could then start a new experimental run and do the REVERSE. Each time they would merely reflect the difference, not whether one was 'right or wrong'. See?
Anyhow, chinglu, if we thus (as above explained) remove all the misunderstandings about philosophical overlays and extraneous variables which have no bearing on the essentials (as I have already done for you in both the SR-only and the GR-only cases), then you must now see it's not a matter of 'right' or 'wrong', but a matter of difference between different states and the associated 'starting standards' applying in those states IF we go on to carry out such experiments FROM whatever current co-moving states applicable to the twins when they 'start' an experiment.
So, mate, you know I am not trolling you or misunderstanding you, right?
If you do know that, then please take my advice and go concentrate on other discussions which you have a better grasp of the essentials of, because you seem to be missing that here, and so confusing all sorts of things into one compounded overlay of confusion on both the SR and GR cases which I have simplified for you to help you see the essentials and not be distracted/confused by the non-essentials.
Good luck elsewhere, chinglu!