The maintenance of health depends on nature (associated with genes) and nurture (associated with lifestyle and living conditions) interactions at an intracellular chemical level. Asthma is a common, chronic lung disease affecting more than five million people in the UK, but there is uncertainty about the development of this disease. This article will discuss the pathophysiology of asthma as a cellular or chemical homeodynamic imbalance of inflammation and bronchial hyperactivity. Understanding of such imbalance supports the pharmacological rationale of treatment. The article will explore what has been discovered to date through human genomic research, introduce some of the theories associated with the development of asthma from a nature-nurture perspective and highlight potential developments in the diagnosis and management of the condition.