Season of birth has previously been associated with allergic disease risk and children born during autumn or winter are more likely to develop asthma, rhinitis, hayfever, and eczema. However, the mechanism by which season of birth is related to disease remains unclear. The epigenome is one method by which environmental factors may alter gene expression that persists over time, leading to an influence upon allergic disease outcome. This analysis will be carried out within the PACE consortium.