incest in Moll Flanders

Well, the incest with her brother is indeed weird, but what I find stranger is the way Moll's "place" in the novel changes in so short a period of time. Moll is seduced by her older brother, set up as his mistress (wife if you like), and then advised to marry her younger brother. It's a travesty. Sister; mistress; wife; sister; sister-in-law; all in a row.