Of all the young women in the novel, Lydia is in some ways the one who is most like Elizabeth: they have the same lively energy that makes them both, in modern terms, sexy. Of course Elizabeth has more brains and sense of responsibility: she's her father's daughter. But she's also, like Lydia, her mother's daughter too, and her mother had enough of whatever it is to make Mr Bennet lose his head and marry her in the first place.