In a study comparing obese versus lean twins, Turnbaugh and colleagues found that there were "shared microbial genes among sampled individuals, comprising an extensive, identifiable 'core microbiome' at the gene, rather than at the organismal lineage level". \u00a0This means that despite having differences in bacterial composition, the "core" functional repertoire of microbiome remains the same\u00a0in obese versus lean twins. \u00a0In this tutorial, we are going to explore these functional differences in two lean twins (TS1 and TS2) and two obese twins (TS19 and TS20) from this study. \u00a0\u00a0Turnbaugh, Peter J., et al. "A core gut microbiome in obese and lean twins."nature 457.7228 (2009): 480-484.