Kasparov was introduced to chess at age 3. My 3 year old doesn't get the idea of taking successive turns, though he knows we both moves pieces or how to move the pieces properly according to their speciality, he just wants to move them. As a result I don't know how much merit I can give the first few years of Kasparov's chess experience. Kasparov was put through a chess academy, starting at a young age. I am sure it took a few years of coaxing to get him to begin actually "playing" real games.
It was just before his sixth birthday that he started playing after looking at a chess problem his parents were trying to solve, and as he writes himself he had never played the game before that. I doubt he was coaxed into playing, but he got very interested in the game soon after learning the rules.
No one has ever achieved so many consecutive wins against the worlds best chess players. And his name was Bobby.