As "human machines"[4] being made up of cells controlled by a brain to influence aspects of behaviour, there must be some influence of biology on consumer behaviour and how purchase decisions are made as well. The nature versus nurture debate is at the core of how much biology influences these buying decisions, because it argues how much is can be explained through environmental and by biological factors. Neuromarketing is of interest to marketers in measuring the reaction of stimulus to marketing.[5][6]