Ah, the old fertility gene. This has been knocked around before in the world of science. Sort of put a trigger in the genetic makeup. I think it was considered against the Constitution and Religions as being forced birth control.
Mine would be a traffic roadblock that checked everyone for signs of road rage or just plain aggressive drivers. Then remove their license for a year.
“War is an ugly thing but not the ugliest of things; the decayed and degraded state of moral and patriotic feelings which thinks that nothing is worth war is much worse.” —John Stuart Mill