SPATIAL GEOMETRY

I'm slowly coming round to the idea that there are 3 types of Maths brains. When I was a kid, I thought there were 2: those who understood Maths at school and thought it a dawdle and those who could not do anything mathematical even if someone was pointing a gun to their head and threatening death, if the kid didn't instantly understand the finer points of calculus. I never understood that. Maths always seemed boring but simple.
My dad always struck me as a reasonably mathematical person, worked in engineering, understood all the calculating etc but then one day mum got him to install fitted wardrobes in their bedroom. I came home from school to a row that went something like: I don't care how much the cornicing cost, you'll have to re-order it... I was puzzled until I entered their room to find dad had cut all the angles wrong on the cornicing right round the room...not just a little wrong but completely inside out, and was trying to convince mum she was overreacting, and that she'd get used to it...needless to say the cornicing was reordered and redone. Now, at the time, this struck me as very strange. When I look at a corner in a room I see instantly which way the angle needs to be cut to meet in the middle, so how did my reasonably mathematical dad make such a colossal balls-up? Maybe he was tired, rushing or whatever...
Now we are trying to sell the flat in Rose street. Thomas, I have always considered, in the 5 years I've known him, to be extremely clever, highly intellectual, and amongst other things mathematical almost to a nerd degree. I've seen the computing database he designed in the office - even Einstein would have trouble following it, it is so complex, and yet he's standing here with two pieces of skirting asking which edge needs to be longest in a way that my dad would be proud of. The genius brain seems to seize up completely in the face of spatial geometry. I'm feeling quite intellectually smug for once (and probably for the only time). So I need to stop blogging now and go draw him a wee diagram to show which way round the angles go ;-)