Bad Parenting

Ophelia has legitimately gone insane, and it is largely due to bad parenting on the part of Polonius. She is a fairly flat character, who, like various other women in Shakespeare’s plays (Gertrude being one of them), is seen in terms of her sexuality, chastity, and ability to reproduce, and shows no evidence of having a mind of her own as she is consistently told what to do and think by the men in her life, particularly her father. Because she is accustomed to having little to no control over her life and to live off of the instructions given to her by men, she becomes lost after her father’s death and goes completely mad. She speaks mostly through song in act 4; this is a moment in Shakespeare play where song is meaningful and the lyrics should be closely considered (like a couple of the songs in Much Ado About Nothing).
Right away, in her talk with Gertrude in scene five, she sings, “How should I, your true love know / From another one?” (IV.v.22). She expresses confusion and is perhaps questioning her feelings for Hamlet which stands to reason given the history of their relationship. Throughout Ophelia’s entire relationship with Hamlet, she has been told how to act and feel by her father and Laertes. In fact, it is quite likely that throughout her entire relationship with Hamlet, she never acted on account of solely her own feelings, without the influence of her father and brother’s opinions and demands. Because of her dependency on her father--especially in relation to her relationship with Hamlet--she is left not only without a father, but also with a lack of direction and mind of her own. 
It is part of a parent’s job to encourage their children to think for themselves and to make their own decisions in order to better prepare them to go out into the world as an individual, away from their parents. Polonius does not prepare Ophelia for a life without him at all. He essentially raises her to be dependent on the men in her life, not encouraging her to develop her own sense of self, individuality, or independence. He does not account for their potential separation/his death and therefore leaves her feeling lost, confused, and vulnerable which leads to her eventual insanity. Maybe it was normal to raise daughters to be dependent on men in those days, or maybe this situation just further characterizes Polonius as being controlling of his daughter. Either way, it is an irresponsible and unfair way to raise a child as it leaves them defenseless against the world on their own. Polonius illustrates a sheer lack of good parenting throughout the play. Not only is he controlling of Ophelia, but he shows little concern for Laertes as well, and when he does concern himself with him, it is only to ensure that he is not tarnishing the reputation of the family as Laertes is said to be somewhat of a reckless young man who gets into trouble without regard for others--a stereotypical product of bad parenting.