Answer and Explanation:
I believe it is safe to say Gregor's family is greatly responsible for his tragic outcome. As a matter of fact, his transformation is also in great part their responsibility.
Gregor's transformation into a bug (possibly a roach) serves to show how he was perceived by others, and even himself. His life was worthless. He existed solely to work a sad and unsatisfying job. The only reason why he did not quit was his family - he was helping his parents pay off some debt. Yet, his sacrifice was not appreciated.
Once he went through the metamorphosis, his family did not in the least try to understand the reasons behind it. They simply went from the initial indifference (when he was still human) to disgust. They could barely lay eyes on him. Indifference grew into completely ignorance of his existence, to pretending he wasn't even there so that they could keep on with their lives. Perhaps, if they had been more humane in their treatment of him, if they had cared at all, Gregor would not have died.