Forward shoulders. When seated, the shoulders can hunch forward and can cause the shoulder to twist, as is the case in the first photo posted. When standing naturally, if the twist occurs on one or both sides, it is because your shoulders are pitched more forward than was accounted for when making the pattern- this can occasionally be fixed by a tailor but it's not cheap. You will usually feel pressure on the shoulder point as well.
9/23/13 at 7:03am