I read a childrens' scifi book in the 60s about a young boy whose parents (I think) were scientists. I think they were working on interdimensional travel before he is born, and when he is born he is gifted. He finds that he is able to 'turn sideways' into another dimension of geometrical shapes and he becomes made up of geometrical shapes too, and travels through it. I'm pretty sure he slips or turns into that dimension when other scientists are after him to study him. The cover had a line drawing of a boy made up of geometrical shapes. Help? It's driving me nuts.