Lots of single-child families, over several generations. That means no siblings, no aunts and uncles, no cousins, etc. Only one adult child to care for elder parents with no support from aunts or uncles. Worse, most are boys and have no sister siblings from which to learn about relationships between boys and girls. When and if these boys marry, the wife has no sister-in-law to help her. China is screwed up.
Central planning. Is there anything it can’t screw up?