Please forgive, but this thread is too funny. I do not mean to be insensitive but people who are experienced with naturism, or been around it, do not think about things like that really. I get the insecurity with boys and, to an extent, the same with my own gender about breast size etc.
Your package reacts as it is a part of nature. A wonderful part of your bodies. All the advice and comments are valid here and the best is to not worry about it! Boys and men? Don't give it a thought!
Or, you can, if you are obsessed with your cock/balls reacting to nature, get one of these.