The young woman in your anecdote is an extreme outlier. First, her family and all families she knew well only had a single child for generations; if that’s the case for most people, the population would shrink rapidly, so obviously most families aren’t like that. Secondly, to be unfamiliar with the concept at all, she had to be unfamiliar with some household names from cornerstones of Chinese literature, taught in grade school; very unlikely for a literate person. She also had to distance herself from television and the like, which was achievable twenty years ago.