[I'll try to keep this post relevant and not make it too much of a ramble.]
While the degree varies from person to person, I think most everyone can agree that Humans need (crave, want..) interaction with other humans (intellectually, emotional, physically...). There is also the basic desire/need to feel wanted and the feeling of wanting someone/something. I think it can be argued that on these basic ideas that Humbert's and Lolita's relationship is simply a Humanistic one -- a form of wanting and being wanted. Then the idea of sexual needs as a basic need for the continuation of a species -- and again part of that desire to have an interaction with another person. Humbert and Lolita's sexual desire works on these two levels. HH even talks about how he should have taken Lo to Mexico until they could marry in the states and then he could impregnate her. But then again, biology had already begun its next phase with Lolita -- so whether she was ready for sexual encounters or birth is irrelevant, because the biological nature of maturation was making her perceive men in a different manner.
Society and Human Nature have a difficult relationship. On the one hand, we only have Society because of the more intricate facets of Human nature, but at the same time, Society suffocates and confines some of the raw facets of Human nature. While there is this involuntary need for procreation, there is also is a definition in Society of what is appropriate in sexual matters. Taboos form and laws are set in place. In this regard, HH and Lo's relationship is wrong. People look at this novel in many lights and (whether you find some readers ignorant or not) find its basic story horrifying. But we look at the novel in such a light because of the way our society has shaped us.
Society and Human Nature
Society can be manipulated to make Human Nature actions reasonable.
Evidence 1) The Bible. Specifically Genesis 19:30-38 (KJ version)
" And Lot went up out of Zoar, and dwelt in the mountain, and his two daughters with him; for he feared to dwell in Zoar; and he dwelt in a cave, he and his two daughters. And the firstborn said unto the younger, Our father is old, and there is not a man in the earth to come in unto us after the manner of all the earth: Come, let us make our father drink wine, and we will lie with him, that we may preserve seed of our father. And they made their father drink wine that night, and the firstborn went it, and lay with her father; and he perceived not when she lay down nor when she arose. And it came to pass on the morrow, that the firstborn said unto the younger, Behold, I lay yesternight with my father: let us make him drink wine this night also; and go thou in, and lie with him, that we may preserve seed of our father. And they made their father drink wine that night also: and the younger arose, and lay with him; and he perceived not when she lay down, nor when she arose. Thus were both the daughters of Lot with child by their father."
This passage can be explained as the daughters thinking they must have sex with their father for procreation, but seeing as how the Bible was written by literate men (in a time when most everyone else was illiterate) it can be argued that they were fitting certain desires into Societal acceptance.
But then there are the complexities of Human Nature that seem entangled in Society. In a memoir by Kathryn Harrison (The Kiss) she writes about a 4year affair with her father.
[ http://www.kathrynharrison.com/thekiss.htm ]. Just reading the reviews shows how life can complicate both Human and Society.
Then there is Maya Angelou's I Know Why the Caged Bird Sings, in which she describes her step-father raping her. And in Sue William Silverman's novel (Because I Remember Terror, Father, I Remember You) she writes of her incestuous father. Or Ralph Ellison's novel (Invisible Man) where the daughter is impregnated by the father. Why do we find these stories so grotesque? Is it because they are portrayed in so hideous a manner?
And what about Oedipus. (Granted, he gouged out his eyes and his mother committed suicide when they found out they were mother and son). But what does their reaction say? Was it adhering to Societal conventions?
Then why do we have such a contradiction in feelings towards Lolita? Is it because Society tells us to hate the subject matter, yet on a most basic level, we can relate to the feelings shared by HH (and those of Lo)?
Maybe it's just too much of complicated mess and each case deserves to be seen for what it was and can't be placed in a tidy container. I mean maybe the idea of incest and what it is and means to use is just inherently part of us; to put it one way- we are all just offspring of incest, seeing as how Adam and Eve could be looked upon as Brother and Sister.
http://tinyurl.com/35hq2p [incest in popular culture- wiki entry]