My relative height

[mtbc]

I am of average height for men but when seated among others, in lecture halls or on airplanes or wherever, I notice that my head is markedly among the higher. I do not have any difficulty buying clothes so I infer that I am not unusually proportioned. I thus guess that my high sitting may arise from my lower back issues: I am sitting so as to get good support from the chair rather than slouching in some way.