Source: https://medium.com/@phacks/how-grigori-p...

Grigori Perelman was born in 1966 in Saint Petersburg. Showing excellent math skills at the age of 10, his mother enrolled him in a math club supervised by Sergei Rukshin, a then 19-year-old, outstanding mathematics teacher, who excelled at teaching young geniuses. Perelman’s natural abilities were intensively stimulated at the club and he rapidly became obvious that he was not only gifted, but also had a highly systematizing mind that could solve nearly any problem without even writing something. According to Rukshin, his teacher and closest friend, he showed no interest in anything except mathematics, and could not accept the idea that the world and human relationship were not as perfectly organized and defined as mathematics are.