Ironically, one of my biggest fears while entering HS was the thought of being forced to shower with other boys after gym class. I wasn't alone with this fear. I expressed this feeling to some of my closest friends, and they too felt the same sense of dread. Truth is, the only reason we were even aware of this being a possibility is because our dads talked to us about it. While our dads tried to assure us that nudity among peers was 'normal' and that we'd quickly get over it, the reassurance didn't matter. Like most boys my age, I was insanely modest and insecure about my own body. Adding salt to the wound was also the fact that I was a late bloomer who just wrapped up a hellish 3 years in middle school.
So you could imagine how much of a nervous wreck I was during the first day of gym in highschool. So towards the end of the first day of gym class, the coaches laid out the outfits that we'd have to wear from then on. By this point, I looked at the clock and noticed there was still a lot of time left before we beginning of the next class. Plenty of time to accommodate the dreaded shower session. I figured this was the moment when my greatest fear was about to be realized and braced for it. As predicted, the coaches wrapped up the first class and then commented on showering. Much to my RELIEF... they said it was optional and not mandatory. Bruh, you could almost feel the tension from the other kids release all at once.
It's only in hindsight, after discovering naturism and coming more to terms with nudity, that I look back and wish I had a somewhat different childhood experience. But even then, I firmly believe that social nudity is best when you're introduced to it at a very early age. I observed this cultural behavior in some of the nordic countries and I believe South Korea is pretty good about this as well. In certain places, like a shower or sauna, it's more or less expected in many parts of those respective countries. This introduces people to nudity at a very young age, which in turn makes them realize that it's no big deal, which gives them a fairly healthy and grounded perspective of the human body, which allows them to grow up without the same anxiety and or sexual associations with it that many millions (billions) of people do!
It's an interesting topic, fo' sho'.