I got a booger as well. So that's 2:2 score on boogers vs boners on this thread so far, I think some one should keep the score.
As far as the story goes, I read somewhere that incest is an expression of narcissism, something about the person loving themselves so much they would like to have sex with themselves. Due to being physically unattainable they choose someone most similar to themselves (from the same gene pool).