Thinking rationally, being shy about our bodies doesn't really make sense -- are there any logical reasons why nudity isn't ok?
One observation though, even the aborigines in Papua would cover up their privates in little tubes or bits of hide. I thought this surprising.
Proximity to an unshielded nudity core can have that effect.
(http://www.imdb.com/title/tt0081249/ -- safe for work)
I always heard in Mexico that German people were very cold and dry. When I visited north Germany about 4 years ago, I was introduced to my aunt's mother-in-law, and as I'm accustomed I went right up to her, gave her a big hug and a kiss on the cheek. Well her reaction amused me, she got in a very cheerful mood and I got an extra spoonful of food at the table. :)
I mean, I don't speak a word of Gaelic or Shawnee.