One of the problems we have is that the onset of POIS is progressive, unless you are one of the unfortunate ones who's had it since puberty.
So one day we feel it, and it just happened to appear at the same time as something else, so it feels like it was that something else that started the POIS.
Unfortunately the relationship, especially at first, is fairly indirect. We have an orgasm, and initially, maybe don't feel the symptoms for a couple of days, so don't relate it to the orgasm. Then the day you put loose boxer shorts, the symptoms star, so it seems to be the boxer shorts.
Who knows. Maybe it IS. But I always ask, "If it's boxer shorts, why don't many, may more have POIS.
It's not a bad question, we have to ask. And we can all answer, but probably won't be sure, even if the majority say that they wear "such-and such" shorts, because we need a control group, who wore "the other shorts", and DON'T have POIS. Then a study that shows the figures for most of the world.
Anyways, I wear boxer shorts, now, but for a good long time, probably even coincident with the start of my POIS didn't wear ANY shorts. I don't have POIS now, but not becasue of the shorts, but because of niacin..
Oh, well. That's why we are doing professional research. It's going to start to become intresting in November.