Excerpt from chesser‘s comment in Hacker News:
Bobby Fischer was completely obsessed with chess and played and studied it incessantly.
9 years of manic dedication and he “suddenly” got good.
His mother spoke something like 8 languages and his father was a Hungarian physicist who headed the Theoretical Mechanics section of the Naval Ordnance Laboratory and was an expert in elasticity and fluid dynamics.
One famous story about his memory:
“One day when he was in Iceland, Fischer called Frederick Olaffson, Iceland’s only Grandmaster. Olaffson’s Icelandic-speaking daughter answered the phone and explained her parents were out and would return at suppertime. Fischer understood nothing that was said because he did not know the language. But he listened, apologized and hung up. Later that day Fischer met with another Icelandic player who spoke English. He explained what had happened and repeated every Icelandic word he had heard on the phone, imitating the sounds with perfect inflection. The Icelandic player translated the message word for word for Fischer.”
Despite being prodigiously “intelligent”, it still took years of dedication to get good, and years more to get really good.
Plenty of average people undoubtedly beat him at chess when he was a kid. When you think about it, it should be obvious that he was always that smart. Just because you’re a kid and don’t know anything yet doesn’t mean you aren’t smart. “Smarts” is not the same as skill.
Incidentally, his record as the youngest grandmaster in history lasted for many years until it was broken by Judit Polgar, whose father was explicitly running an experiment with his daughters to prove that prodigies are made, not born. All three daughters became chess experts. He explained that Judit, the youngest, was the most successful because she worked the hardest. She’s the only female ever ranked in the top-10 of the “Men’s” ratings list.