There are several new frontiers in gene-environment interplay research with potential relevance for prevention science (e.g., recent work on epigenetic effects). One such frontier is the study of the human microbiome. The microbiome is the collection of microorganisms (and their genes) associated with a particular animal or plant host. There has been an explosion of research regarding microbiomes in recent years (see Cho & Blaser 2012 for a review). Recent research, for example, has shown that the composition of the human microbiome varies across individuals and can be as distinctive as a fingerprint (Franzosa et al., 2015) and that humans emit a “cloud” of microbes that can potentially result in transfer of microbes across individuals (Meadow et al., 2015). The composition of the human microbiome has been linked to a number of important human physiological traits, including effective digestion and maturation of the immune system, as well as the incidence of important health disorders such as asthma, inflammatory bowel disease, and obesity (Cho & Blaser, 2012). The human microbiome has also been recently linked to sleep patterns, mood, and other
