And the implication(probably fully intended by Hugo) is that Esmeralda, despite her flightiness amd superficiality, is a good person and should be treated in the same way as White French people because she is one of them, and not really Roma. i.e. "blood will tell", a person's ancestry, their racial origin, determines their personality and morality, not how they were raised and their own emotional reactions. So the other implication would be that Quasimodo, although he was raised by White people, will (as revealed by the plot twist that he is of Roma ancestry) have a bad streak because he is Roma.