What are some uncontrollable forces—for example, family—that play a role in Shakespeare's Hamlet?

Well, it certainly is true that we can’t pick our family.  Hamlet cannot change the fact that his uncle is corrupt and ambitious enough to murder his own brother for the throne.  However, Hamlet does try to influence his mother’s unvirtuous behavior with Claudius. After he berates her for her poor judgment in entering into what he sees as an incestuous relationship with her former brother-in-law, she admits to Hamlet that his words have cut her heart in two.  He tells her, “O, throw away the worser part of it, / And live the purer with the other half!” Gertrude, however, is right back in Claudius’ arms the minute Hamlet leaves the room, so his efforts are to no avail.

Tied with family is the concept that we can’t control the circumstances we are born into. Hamlet is the prince, whether he likes it or not. As Laertes warns Ophelia, Hamlet may not choose his own wife, “for he himself is subject to his birth.” He will be married to a woman of royalty who can politically strengthen Denmark. Ophelia is also subject to her birth. Besides the fact that she isn’t royalty and not considered worthy of the man she loves, she was born female. Women of the middle ages, in which the play Hamlet is set, weren’t considered capable of making most decisions for themselves, and were required to obey the men in their lives. Under the pressure of constant control, losing Hamlet, and burying her father without her brother’s presence, the only choice she is able to make for herself is to simply stop living.

Another uncontrollable force in Hamlet seems to be the supernatural world. As the guards and Horatio wait for the apparition to reappear, Horatio recounts past supernatural happenings that seemed to foretell ominous events, such as ghosts in the streets, a comet in the sky, and an eclipse of the moon just before Julius Caesar was murdered. The men feel powerless. They cannot make the ghost speak to them, yet they fear it foreshadows some disaster for Denmark. Hamlet himself is unable to command the ghost. Although it will speak to him, he feels bound by filial obligation to commit the revenge it requests, since it appears to be the spirit of his murdered father, the former king. He is also unable to make the ghost reveal itself to Gertrude, so that she decides Hamlet is completely insane and discounts all that he has labored to convince her of concerning Claudius.

Considering all that is beyond his control, it is no wonder that Hamlet is suicidal and so easily overcome by his own ruse of insanity. Yet in the end Hamlet takes control of his own attitude and makes peace with his fate. He tells Horatio, “There is a / special providence in the fall of a sparrow… / if it be not now, yet it will come. The / readiness is all.” He might not be able to control when his death comes, but he feels ready for it when it does.