Our sexuality isn't acceptable in the Christian world, but a vast number of cultures down the centuries have regarded it as quite normal and many still do, though finding evidence of its prevalence in the modern day is hard work; you find it in occasional reports from Afghanistan if you look really hard, e.g.

http://www.foxnews.com/story/0,2933,44067,00.html

though that has a very negative spin on it, though the suggestion that 15 year olds are innocent is... blinkered.