Given the potential importance of the microbiome in human disorders central to the study of prevention science (such as behavioral disorders and obesity), understanding the interplay of the human genome, microbiome, and environment in influencing human traits is an important topic for prevention science research. The naturalistic experimental designs described in the preceding sections could be used to ask fundamental questions about this interplay by collecting and analyzing microbiome samples in adoption, cross-fostered, or IVF samples. Several recent studies have used twin designs to ask questions regarding the importance of genetics in determining the composition of the human microbiome (e.g., Goodrich et al. 2016), but the use of natural “common garden” or “cross–fostering” approaches in human populations to partition the effects of genetics, the microbiome, and the environment and examine their interaction would add to the field of prevention science by helping to identify specific environmental attributes that influence the microbiome and potentially offset inherited health risks.
