at one's mother's knee
US /æt wʌnz ˈmʌðərz niː/
UK /æt wʌnz ˈmʌðərz niː/

1.
从小, 在母亲膝下
from a very early age; from childhood
:
•
He learned to play the piano at his mother's knee.
他从小就学会了弹钢琴。
•
She was taught good manners at her mother's knee.
她从小就被教导要有良好的举止。