How is nature versus nurture portrayed in In Cold Blood?
Capote portrays their idea of "nature vs. nurture" in Dick and Perry. Capote shows sympathy for one of the men, based on his upbringing, and shows the other to be a "natural born killer."
Capote paints Perry as a sympathetic character. Capote describes Perry's terrible childhood, with parents who didn't get along, a mother who abandoned him and his sibling, his father moving around all the time, and a sister who committed suicide. Capote goes into great detail, describing Perry's dreams and aspirations, making Perry almost naive and childlike with all of the memories--letters, photos, books, etc.--Perry carries with him in big boxes. Perry is also severely injured, with legs that are smaller than they should be for a man his age. Therefore, Capote plays on the reader's sympathy for Perry--one can't help but feel sorry for him regarding his situation while growing up, and blaming that for the fact that he turned to a life of crime.
Dick, on the other hand, came for a very normal sounding background. He has loving parents, was an award winning athlete in high school, and has many girlfriends. In comparison to Perry, Dick seems to have little to nothing in his background to indicate his upbringing would turn him to criminality. Therefore, Capote must believe that Dick's criminality is inborn--or a result of nature.
It's interesting to note, however, that it was Perry that did the killing, even though Dick is the one who brags about violent acts more, and Perry makes them up to impress Dick. Perhaps this is Capote's way of indicating he is more in favor of criminality being born by nurture, rather than nature.