Like Rhiannon, I've always thought of the nakedness of Adam and Eve to represent innocence and when they discovered greed, pride, guile, lies etc, their innocence was stripped away. It's an allegorical story of people not being ashamed to hide anything and then uncovering a different side to their nature that they had hitherto been unaware of; for the first time they were ashamed of themselves, and wanted to hide (not boobs and willies!).