If you read biographies of gedolim, you will hear stories of how they were raised. Their parents didn’t know they would be a raising a “godol hador” but raised them with a deep appreciation for limod hatorah and a deep sense of being a “yorei shamayim”. It has been reported that Rebbetzin Karelitz (mother of the Chazon Ish) put yarmulkes on her sons from 8 days old and washed neigel vasser with them from the time they were 30 days old. They also say that she was makpid that the walls of her house not see her hair and would wash her hair for shabbos with others holding towels above her head.
I heard in the name of R’ Moshe that when he was 9 or 10, he learned the entire Mesechta Beitzah with his father on Shavuous and felt he had a very deep understanding of muktzeh from that learning.
On the other hand, R’ Yaakov Kaminetsky when learning in Sladboka brought home a younger talmid and when R’ Yaakov’s mother saw the boy asked “Who is he? The shechina is shining from his face”. The Bochur? R’ Aharon Kotler (who was a teenager at the time).
It is a well known story that R’ Aharon’s family kept writing letters to him telling him to leave the Yeshiva and go to University and study math. The Alter had Reb Reuvain Grozovsky intercept the letters.