PARIS, May 4 -- What do Harry Potter, Hazel Lancaster and Katniss Everdeen have in common? They're all heroes of "young adult" fiction As the name suggests, this literary genre is generally aimed at teenagers, but it reaches a much wider readership than you might imagine, as a survey by publishers HarperCollins and Farshore reveals.

The figures speak for themselves: 74 per cent of readers of young adult novels are over 18. The 18-22 age group is particularly fond of this type of fiction (28 per cent), as are the 13-17 age group (23 per cent). The heterogeneity of the young adult readership can be explained by the fact that, these days, "youth" seems to last longer and longer.

This is one of the great paradoxes of our society. We're seei...