Ive been seeing a physio at work for a shoulder injury,today she asked me to do various stretches and one of them was to touch the backs of my hands together above head without bending the elbows,only managed to get arms up to 10 past 10 position,she said that was very poor and i was muscle bound from going to the gym and most likely from overdeveloped upper traps.
She showed me how easily she could do it and said most people should be able to do it but she's only about 8 stone max.
Little test,can you just try and do this and post how far you can get.
As pic but backs of hands touching