
It is agreed that WJ Sidis had the highest known IQ. He lived an unfocused and unproductive life. I have known many like him. He looked exactly like a childhood friend of mine who signs his emails
Osiris (lately only the Egyptian symbol of that god). He has the same expression. But it is not William James Sidis whom I find astonishing, but his mother.
Her autobiography is on the web. It is short, to the point and readable.
She was born in a godforsaken Ukranian shtetl in an ultraortodox family (We were all ulraorthodox then, so it would be ebough to sya that they were Jewish). Her parents married while he was at the yeshive (at 17) and had fifteen children. Then the Tzarist regime started the pogrom program (progrom IS program with Russian pronunciation) and they had to run and take refuge in America. She went to the university and became a doctor, which was unusual for girls of her generation. All in all, the Sidis story is the typical Russian Jewish story. Why, then, astonishing?
Because in her autobiography she gives not even the smallest indication that she is a Jew, that all her family is Jewish, that they spoke Yiddish and kept kosher at home, that they had to escape Russia because they were Jews, in fact, she forgets to mention (that is, she hides) the most basic, most defining facts of her life. Amazing.
The Sidis were idealists/Socialists/Communists and so, atheists. They believed that their own tribal past is irrelevant - that they were essencial human beings without any other - atavistic - identity.
These were the most intelligent people ever born. They hated themselves. Unfortunately, the world agreed with them. They hated them. Sidis the son had problems all his short life - was sent to jail, was beaten by his collegues at Harvard, was sacked from his job and could never keep one. They wanted passionately be only human beings, to forget that they were Jews, but the world would not let them.

Update (June 28, 2010): I retract my former opinion that he spent his life irrationally. The man learned very early that he could earn a living without problems, so he looked for jobs suited to him - undemanding jobs he could navigate effortlessly and leave him much free time to pursue his own interests. He got a calculating job on Wall Street, but he escaped as soon as people discovered who he was and expected more from him. This lifestyle is more or less the one I adopted - I am designing systems that are ridiculously simple for me, so I would have time to study the market. Unfortunately I accept too much work and spend less than necessary time on the market. I dreamed spending days on the Ehad HaAm street coffees paying attention to what people was saying, yet not once I got there.
Secondly, Sidis spent time thinking about the transfer problem, how to reach from one point in a big city to another point using the minimum transportation transfers and minimum time and/or money. It is a diabolically complex calculation, which was solved only after the invention of cheap computing. People is doing this mental calculation all the time, so an universal/general solution would have been very useful.
Sidis's problem was that surviving was no challenge for him, and he felt no need to conquest any difficult goal that would occupy his forces. In Wall Street he could have applied himself to make a fortune, but he didnt feel like he needed it. My case was very different, coming from the post-war generation that had no relatives nor money nor security, I always forced myself to pursue long term very difficult projects. Which I completed (and
that is another problem).