子供は３歳までに一生分の親孝行をする（こどもはさんさいまでにいっしょうぶんのおやこうこうをする）

Japanese vocabulary

Meaning: children pay back their debt to their parents in full by age 3 (through their cuteness)

See it used in real works

• Example sentences from Japanese novels & web fiction (Massif)
• Hear “子供は３歳までに一生分の親孝行をする” pronounced in real videos (YouGlish)