I was raised without curtains. And I have a couple of theories about why...
1. Light is good. We all need light in our lives, and the more the better. It is healthier and more natural for our bodies to rise and fall according to the sun.
2. No curtains means that the windows can be open wider. Open windows are good. They let the breeze in. They let you listen to your neighbors, and allow the neighbors to listen to you. The more open the window, the more a part of the community you become. (I think this is why my parents have never had air conditioning.)
3. Really, privacy is not something that is necessary, in a community where people share goods, share relationships, share conversations, and share most everything else. There can be spaces in your home which are private, but most spaces by the window were meant to be shared. (Just as doors are meant to be open).
However, here in Colombia, our language tutor Marta could not handle that we did not have curtains. Not only was she worried about others "looking in" on us, but she thought that the reason we all had colds was that too much air was coming in through the windows and they needed to be covered in order to prevent "gripe."
And, I do admit, that privacy is something I value a bit more here, where I do not know my neighbors (and there are 1000s of them living next door.)
So, Marta called her friend the seamstress, and took me to the fabric store, and the result was this:
(they are even prettier in real life)