It is mostly Juliet’s family that the audience sees in Romeo and Juliet, but they are dysfunctional enough to be a play all by themselves.
The underlying problem is the feud between the Montagues and Capulets. To carry on such a feud that can so easily erupt in violence for so long is certainly the essence of dysfunctional. Even the old fathers try to take part in the feuding.
Another aspect of the Capulet’s dysfunctionality is their insistence that Juliet marry Paris even when she says she doesn’t want to. Her father does not calmly discuss the matter with her, but instead forces her away by raging at her about it.
Because of their families’ attitudes, Romeo and Juliet both have to sneak around, which ultimately leads to the misunderstandings and miscommunications that result in their deaths.