Unfortunately, your question had to be edited as it actually contained more than one question. Please do not ask multiple questions. I will respond to how theme is influenced by biographical details by refering to "Once Upon a Time" by Nadine Gordimer.
Quite clearly, if we look at the story, one of the major themes is that of fear and how it can dominate our lives. As shown by the frenzied efforts of the parents to gain the best in security for their home and the ever higher walls that divide them from others, fear is the dominant theme. Of course, tragically and shockingly, the attempt of the family to protect themselves is ironically turned against them as the latest measure, the famed Dragon's Teeth fence, is turned against them as their son becomes caught in it. We are told that the efforts of the parents to protect themselves result in them having to hack out "the bleeding mass of the little boy." Gordimer thus strongly suggests that when fear is allowed to rule our lives it is our own lives that are stunted and impacted.
It is important to be aware of the social background of this excellent, shocking story. Until the 1990s, apartheid ruled in South Africa, which was the legal separation of races. Nonwhites, as a result of this policy, experienced sanctioned racism and discrimination, and were forced to live away from whites that bordered white cities. This of course resulted in massive social problems, especially crime, as blacks robbed their white fellow citizens.
I hope this helps to answer your question. You could successfully compare this story to "The Rocking-Horse Winner," looking at the way that in that story greed is the emotion that rules the mother, only to end in tragedy. In both stories, whether through fear or greed, the son dies as a result of the parents' obsession.