Getting rid of pests was the problem, and it was a real one...
Killing all the sparrows was a legitimate attempt to help that backfired.
Overpopulation was and still is a problem.
One child would have theoretically been managed, but ignored how people act individually and the desire to have a son. An honest and legitimate attempt to mitigate a real problem backfired.
I feel it's an apt comparison, even if I didn't explain enough at first