I would like to point out that the writing was on the Wall for China when it came to the One Child Policy.
Seriously, it's written in their records dating back thousands of years, ever since China started pushing the Patriarchal society. Namely that female children in times of hardship where parents are limited by a lack of resources, will always pick the male child. Female children are often left to die by the roadside or sold as slaves (forget the Chinese word for it). They cannot pass on the family name and are essentially worth less than male children as a result.
Every single time there was a famine they had this repeat.
That they didn't predict this when instituting the policy was... more than a little shortsighted.