I've quickly read the blog post. Indeed, every comment here agrees on the recipe : wealthy family, private/personal tutoring and gifted children to begin with.

But it seems, when asking if it can still be reproduced nowadays, no one here mentions the negative factors, the "inhibitors".

I think social medias, tv (less nowadays), an education system less focused on core knowledge and more on "social" trivia, without mentioning a society that just is/seems giving less praise to smart people or intellectual achievements is not a soil from where geniuses can grow.

People love to mention "low hanging fruits" but for music, philosophy or writing, there are no "low hanging fruits", yet I hope no one is gonna question the fact we don't see new Platos, Mozart or Hugos emerging...