Significance First, our work provides critical biological interpretation of intermediate DNA methylation readouts at the nc886 differentially methylated region (DMR). nc886 was identified in multiple large-scale epigenome-wide association studies (EWAS) that did not recognize that this region acts as a contiguous DMR imposed by genomic imprinting, highlighting the need to reexamine several 450k data sets. Second, strict control of genomic imprinting was thought to be required for organismal viability. Reports of polymorphic imprinting are limited to specific tissue types such as placenta and brain. In blood and somatic tissues, we show nc886 imprinting is mosaic in the population and influenced by maternal environment.