Identical Twins Doubly Exchanged at Birth—A Case Report of Genetic and Environmental Influences on the Adult Epigenome

Aim: Epigenetic comparisons within monozygotic twin pairs have enhanced our understanding of nongenetic mechanisms underlying disease etiology. We present epigenetic findings for a unique case of doubly exchanged Colombian male monozygotic twins raised in extremely different environments. Results: Using genome-wide DNA methylation data from cheek swabs from which blood-specific differentially methylated probes had been removed, the individuals grouped by shared genetics rather than shared environment, except for one twin who presented as an outlier. Closer inspection of DNA methylation differences within both reared-apart twin pairs revealed several genes and genetic pathways likely to be influenced by the rearing environment. Conclusion: Together with our previous findings, we suggest that genetics, pre- and postnatal environments contribute to the epigenetic profile, although additional studies are needed to quantify these effects.