I'm with you Bags - my girls would get in the bath with their dad when they were little, so the male body was not some big mystery to them. It reminds me of that bible story of Adam and Eve, when they had to cover themselves because they had become ashamed of their bodies.
At my convent school, which did not have single man on the premises, we changed after gym in a communal changing room, and the contortions we had to use to prevent any other girl seeing our underwear were wonderful to behold. Boy, were those nuns good at instilling guilt!
At the other extreme, I never forced girls to use communal showers on the odd occasion I had to take a PE or games lesson, because I thought it was cruel to force them if they were embarrassed.