There are few writers Martin Amis admires as much as Vladimir Nabokov, which makes this all the more insightful (from guardian.co.uk):
The word we want is not the legalistic “paedophilia”, which in any case deceitfully translates as “fondness for children”. The word we want is “nympholepsy”, which doesn’t quite mean what you think it means. It means “frenzy caused by desire for the unattainable”, and is rightly characterised by my COD as literary. As such, nympholepsy is a legitimate, indeed an almost inevitable subject for this very singular talent. “Nabokov’s is really an amorous style,” John Updike lucidly observed: “It yearns to clasp diaphonous exactitude into its hairy arms.” With the later Nabokov, though, nympholepsy crumbles into its etymology – “from Gk numpholeptos ‘caught by nymphs’, on the pattern of EPILEPSY”; “from Gk epilepsia, from epilambanein ‘seize, attack'”.’
In fiction, of course, nobody ever gets hurt; the flaw, as I said, is not moral but aesthetic. And I intend no innnuendo by pointing out that Nabokov’s obsession with nymphets has a parallel: the ponderous intrusiveness of his obsession with Freud – “the vulgar, shabby, fundamentally medieval world” of “the Viennese quack”, with “its bitter little embryos, spying, from their natural nooks, upon the love life of their parents”. Nabokov cherished the anarchy of the inner life, and Freud is excoriated because he sought to systematise it. Is there something rivalrous in this hatred? Well, in the end it is Nabokov, and not Freud, who emerges as our supreme poet of dreams (with Kafka), and our supreme poet of madness.
One commonsensical caveat persists, for all our literary-critical impartiality: writers like to write about the things they like to think about. And, to put it at its sternest, Nabokov’s mind, during his last period, insufficiently honoured the innocence – insufficiently honoured the honour – of 12-year-old girls. In the three novels mentioned above he prepotently defends the emphasis; in Ada (that incontinent splurge), in Look at the Harlequins!, and now in The Original of Laura, he does not defend it. This leaves a faint but visible scar on the leviathan of his corpus.