How can someone hate their own daughter?

I have a relative who's been calling me for years and complaining bitterly about her own daughter. It started when the girl was a teenager and I know teens can be difficult but the girl is now 22 and is away at med school. She hasn't lived at her parents house in years, she pays her own bills and the mother is still complaining as if the girl is some sort of pest. Her complaints about the girl are her only conversation and they're really bitter. Some seem to be fabricated as the two have so little contact that the stories she tells are impossible. Has anyone ever heard of such a hatefully obsessed woman? It's almost like she'd prefer to have a drug addict welfare recipient for a daughter than a doctor.