What is the "nature/nurture" question? How does it enter into this novel?

Nature vs Nurture is all about child rearing. Children raised without nurturing parents (or parent) are beholden to no one. They have no emotional attachments, no individuality, and no sense of true belonging. They are raised by the state, allegient to the state, and dependent on the state.

The following excerpt comes from Huxley.net

"BNW is a benevolent dictatorship - or at least a benevolent oligarchy, for at its pinnacle there are ten world controllers. We get to meet its spokesman, the donnish Mustapha Mond, Resident Controller of Western Europe. Mond governs a society where all aspects of an individual's life, from conception and conveyor-belt reproduction onwards, are determined by the state. The individuality of BNW's two billion hatchlings is systematically stifled. A government bureau, the Predestinators, decides a prospective citizen's role in the hierarchy. Children are raised and conditioned by the state bureaucracy, not brought up by natural families. There are only ten thousand surnames. Value has been stripped away from the person as an individual human being; respect belongs only to society as a whole. Citizens must not fall in love, marry, or have their own kids. This would seduce their allegiance away from the community as a whole by providing a rival focus of affection. The individual's loyalty is owed to the state alone. By getting rid of potential sources of tension and anxiety - and dispelling residual discontents with soma - the World State controls its populace no less than Big Brother."