Let me suggest 5 major drivers:Meritocratic civil service exams encouraged heavy investment in education. China institutionalised this first, but the system then spread across East Asia. Education became seen as the pathway for social mobility.Education fever has spawned an arms race of intensive parenting.Within China, fertility fell earliest in the more individualist northeast, where there is less onus on lineage.Economic development has spawned cultural liberalisation, weakening pressure to b...