A physio told me once that I have 2 slight curvatures in my spine. They cancel each other out and aren't obvious as far as I know. I sort of need a wheel alignment. I do know that my shoulders work differently, left and right do not work symmetrically and back thickness is a bit different through the upper back as well. I don't know if the curvatures have anything to do with it or if it's due to injuries but my posture is not square and there are muscular variations.