The central question is what developing an idea of children in the singular has done to Chinese society;

不知网友从哪里看到这个句子的。独生子女政策用Developing an idea of children in the singular来表示感觉很奇怪的。网友在理解这个表语从句的时候断句错误，因而觉得不好理解。这个what不要和developing连起来读。what是has done的宾语，动名词短语developing...是主语。

独生子女政策可用one-child policy， 多简单。

What has one-child policy done to Chinese society？

The central question is what one-child policy has done to Chinese society.