I used to have a pretty bad winged scapula as a child. My shoulder joint was also very loose. Lifting weights took care of both for me. I can still push out my scapulas if I want but I'm not nearly as flexible as I used to be.
Edit: And oh, my body is also pretty unsymmetrical. There's gotta be something about the bone structure. Although I may be imagining things I think my left clavicle is longer than my right and all my muscle bellies have different shape. It's not apparent or annoying but I can see it.
