Concerted efforts over past decades have established a thorough understanding of the canonical somatic DNA methylation landscape as well as its systematic misregulation across many cancers. However, the underlying mechanisms that may direct this genome-scale transformation remains elusive, with no clear model for its acquisition or understanding of its potential developmental utility. I will first summarize work from the past decade that provided key insights into our general understanding of DNA methylation and then discuss recent data that provide evidence for a developmental origin of the shared, erratic cancer methylome.