This post is going to sound like an ad. Sorry about that. I'm not affiliated, etc, etc.
Last Friday I bought a very simple toy: a set of 216 little magnetic metal balls, about the size of ball bearings. Since then I've been completely entranced by it and unable to put the thing down. Here's a Flickr group to show what I mean. The little balls seem to want to come together in symmetrical patterns: you can make square and hexagonal flat patches, curved patches with 3/4/5/6-fold symmetry, stable 3D cubic lattices, fcc and hcp lattices and many hollow and solid polyhedra. So far I've managed to make a tetrahedron, two varieties of cube (1, 2), an octahedron, an icosahedron, and other stuff (my current favorite shape is the solid truncated octahedron). It's like crack for the right type of person.
And there's the rub. Carrying this toy around and showing it to my friends has made me realize with forgotten clarity that I'm special. Practically no one reacts to it the same way as me. The word "aspie" has been uttered, half in jest, half seriously. Even though my intelligence may be pretty average (judging by online tests I have lower IQ than most LW regulars), I seem to have this rare natural ability to get deeply interested in things that "normal" people find boring.
This ability... this instinctive desire to tinker with symmetrical patterns... has shaped my entire life by now, because it's what first attracted me to math and then programming. But how could it ever be environmental, if I remember having it since my earliest childhood? Is it genetic? Is math success genetic, then? What do you think?