The study by Rothschild et al. (2018) published in *Nature* investigates the factors shaping the human gut microbiota. The researchers analyzed data from 1,046 healthy individuals of diverse ancestral backgrounds, finding that the gut microbiome is not significantly associated with genetic ancestry and that host genetics play a minor role in determining microbiome composition. Instead, they found that over 20% of the variability in microbiome diversity is linked to environmental factors such as diet, lifestyle, and anthropometric measurements. The study also demonstrates that the gut microbiome significantly improves the prediction accuracy for various human traits, such as glucose levels and obesity measures, compared to models using only host genetic and environmental data. These findings suggest that microbiome alterations aimed at improving clinical outcomes can be effective across different genetic backgrounds. The results are further validated in a Dutch cohort, reinforcing the conclusion that the gut microbiome is predominantly shaped by environmental factors.The study by Rothschild et al. (2018) published in *Nature* investigates the factors shaping the human gut microbiota. The researchers analyzed data from 1,046 healthy individuals of diverse ancestral backgrounds, finding that the gut microbiome is not significantly associated with genetic ancestry and that host genetics play a minor role in determining microbiome composition. Instead, they found that over 20% of the variability in microbiome diversity is linked to environmental factors such as diet, lifestyle, and anthropometric measurements. The study also demonstrates that the gut microbiome significantly improves the prediction accuracy for various human traits, such as glucose levels and obesity measures, compared to models using only host genetic and environmental data. These findings suggest that microbiome alterations aimed at improving clinical outcomes can be effective across different genetic backgrounds. The results are further validated in a Dutch cohort, reinforcing the conclusion that the gut microbiome is predominantly shaped by environmental factors.