Two television adaptation of Sara Shepard's teen novel series, Pretty Little Liars and The Lying Game, and two L.J. Smith teen novel series television adaptations, The Vampire Diaries and The Secret Circle (see also by neither of these authors, TV series like Revenge and Caprica with a similar dramatic structure) all have a powerful theme that give them verve and broad appeal, in addition to their focus on secrets and lies.
Each one plays up at some level in its plot structure the notion of intergenerational betrayal. The middle aged parents of each ensemble casts of teen heroes and heroines have deeply betrayed or failed them and their generation.
For teens, this captures of zeitgeist of a generation that feels that its been given a raw deal through no fault of their own. For people in the generation of those parents, the reaction is more along the lines of reassurance that however badly we have failed our own children, at least we have not wronged our own children quite so severely, therefore we must be at least half decent parents by comparison. It is a different appeal, but a real one.