Would the Victorian reader have been expected to consider Tess's lineage significant? What theories of the day would have prompted concern with "degradation?"

Tess of the d'Ubervilles created a great deal of controversy when it was published, mostly on account of its treatment of sexuality. However, the novel’s critique of Victorian sensibilities extends to considerations of class privilege as well. It’s clear that Tess’ “noble” heritage, if not exactly a sham, is not worth much in practical terms, just as it is clear that the parson who tells her father about his lineage is playing him for a fool. Victorian readers would understand this, but I think many of them would find it more offensive perhaps than modern readers do. Hardy inverts class in the same way he inverts sexual morality: Tess is “pure” despite her sexuality, and perhaps more truly “noble” than Alex, who actually possesses the D’Urberville name.
No doubt some Victorian readers saw this inversion as a kind of “degradation.” Victorian notions of race were complex, but based on Darwinian notions of the “stages of man” and the idea that certain ethnicities were more advanced than others (Anglo-Saxons, for example, were considered higher on the evolutionary scale than the Irish). Hardy’s empathetic treatment of Tess as a woman from the lower orders was also a powerful critique of that sort of racism.