So that was probably her mother. Who attempted to kill her when she was younger, partly out of rage for 'ruining' her and partly from the syphilis literally eating at her brain. :-(
I theorise that's why MaoMao first became interested in poisons - looking for a cure. (If I was going full Freudian I could make some hay out of her self-mutilation [*German accent* ahh, she wishes to take on the burdens of her mother] and masochistic self-poisoning [yess, yess, you believe you deserve to be punished for living].) Might also be how she became so... flat; don't react, and she won't get mad.