Quite a few genetic polymorphisms have been identified that associate with painful medical conditions. There is remarkable variability in the amount pain that different people experience. Individual differences in pain response are traditionally attributed to psychosocial and cultural factors, personality, personal inclination and upbringing – in brief, to environmental factors. Most biological traits are affected by genes, environment, and interactions between the two. Pain response is likewise affected by nature as well as nurture. It is essential to realize that genes code for protein molecules, not for sensory and emotional experiences such as pain. Genetic polymorphisms do not affect pain response by an action on the psyche, but rather by altering cellular functions. Finding genes that alter pain response to experimentally applied stimuli is relatively straightforward using the genome-wide association study (GWAS) approach. Finding genes that predispose to pain due to disease or injury is more challenging.