I worked in the legal cannabis industry & I'm pretty sure it's just old puritan values for the most part. There's also a large history related to alcohol prohibition. Long story short, the government agency that handled enforcing prohibition needed something to do after prohibition ended. Then came waves of propaganda associating weed with black people, mexicans, and gays to make white people scared of it. Isn't it kind of weird that we call it marijuana in federal laws? Before, it was all just called "hemp". Nixon ramped it up and created the beginnings of our modern prison state. The US is the most incarcerated country in the world both by per capita and total number (1). Mass imprisonment became a way steal votes away from these communities as well as create a more palatable version of slavery where we currently have people working for $0.25/hour.
The reason why so much research is just coming out now is because it was illegal to study the plant. So it's kind of backwards to say the fertility or any other non-obvious effects inspired criminalization as no science was done until it became legal enough to study.
(1) https://www.statista.com/statistics/262961/countries-with-th...
