This is new to me. Is there legit scientific study for this? If so, I can only imagine it's not very popular, regardless of where the data actually points. Is it possible this phenomenon may also be partly due to the increased use of hormones in cattle and poultry that gets mass processed into fast food? Or even certain type of pesticide use on crops?

I don't know specifically of any study. And yes, in pollution I also include pesticides and hormones. What I'm doing is just observing the differences between and within countries and there seems to be some outside, non social influence.