Girls are often called “Too many” or “Little mistake”. In the 1800s there was a famine in the PRC which led to an outbreak of civil war in Huaipen.
Girls were killed because they were another mouth to feed. The boys then grew up to have no one to marry. There were hundreds of thousands of unmarried men, who became rebels. They almost overthrew the emperor.
Now there are 100 women for every 117 men. 80 million men have no hope of (heterosexual) marriage (or just marriage if they stay in the PRC). The age gap between couples has only exacerbated this. Old grooms will take teenage wives which only makes the situation worse for the next generation.
There are now whole bachelor villages refered to as “bare branches”. They used to become monks, soldiers or eunuchs. Now they move into the cities.
There has been an outbreak of female abductions, where women are sold to families looking for daughters in law or as prostitutes for male dominated cities. Selective abortion has been banned by the government with the official statement “girls are fine descendants too”.