I replied to this earlier, but it seems not to have landed in LuLa, or I was distracted and went off to do something else. Anyway.
My classic sense of visual equilibrium has zilch to do with a sense for mathematical geometry: I only managed to get high enough grades in maths during my engineering apprenticeship because my girlfriend patiently tutored me through to a level enough to scrape past the critical line! I have zero natural feeling for maths.
Life is basically unfair, but then if it were, we'd all be interchangeable which, of course, wouldn't do at all.
:-)