Gut microbiota composition is shaped by environmental factors as well as host genetics. Whether diet-induced manipulation of gut microbes is reproducible across genetically diverse individuals remains unclear and is an important consideration from a therapeutic perspective. Carmody et al. (Cell Host & Microbe Volume 17, pp. 72–84) show that diet can reproducibly overrule genotype-related differences in shaping the murine gut microbiota. Depicted on the cover is a visual representation of the balance between host genetics and diet in shaping microbiota. Also, see the included Perspective article by Jens Walter.