A large scale genome-wide association study has constantly indicated that certain several genetic variations among tens of thousands of genes present in the human genome are associating with the onset of allergic diseases. Although their associations were highly statistically significant having P-values of <5x10^-8, the odds ratios were quite low. Since we hardly perceive their significance by seeing patients, or by intuition, only these large scale genomic or epidemiologic studies seem to generate new hypotheses such as the role of IL-33 or skin barrier function on the development of allergic diseases. These newly generated hypotheses are expected soon to be demonstrated in the near future and will bring new paradigms regarding our understanding of allergic diseases.