Translation of Idiosynkrasie

From time to time I listen to my old CD collection. However, most of the CD boxes, meaning the covers, are so full of dust that one can hardly see the image. Taste changes with the age, that is known.
The short story 'Hills like white elephants' is a short story about a relationship between a man and a young girl, based on having sexual encounters. The meaning of this story is not immediately recognizable.
My wife and her started a nice conversation and the village girl did not believe that my wife was older than thirty years old. My wife considered herself as old, but the little girl explained her that she wasn't.