‘You should wait until you are older to date.” Growing up in a working-class family in China, I learned this at an early age. Like many Asian parents, my mother stressed the importance of working hard and getting a good education before beginning a family.

Having a child outside marriage never crossed my mind. In the small city where I grew up, it isn’t done. Even today, less than 4% of births in China are out of wedlock, and the same is true in India, Japan and South Korea. For the vast majority of young adults in Asia, the...