Debunked: https://www.ncbi.nlm.nih.gov/pubmed/19524224
"Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2721724/
There was an inverse association between soy food intake and sperm concentration that remained significant after accounting for age, abstinence time, body mass index, caffeine and alcohol intake and smoking. In the multivariate-adjusted analyses, men in the highest category of soy food intake had 41 million sperm/ml less than men who did not consume soy foods.
The implicitly suggested volume measure might not be the wrong measure either since fertility depends on quite a few variables, several we don't even know about.
These unknowns are actually a bit concerning on their own since fertility has been falling rapidly, at least in most of the western hemisphere, and the cause is unknown.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1480510/
At least it's several times bigger than European and USA consumption.
Citation required for what? The fact that they eat more soy?
Demonizing soy is just a fad. Like demonizing meat or dairy.
Most of USA and Europe eats female mammals like cows and chickens, are we going to make claims that female animal estrogen contained in that flesh makes men infertile? Seems like a much more probable cause than phytoestrogen from plants, not that I would be irresposible to make that argument without any evidence, as is the case for soy.