Scientists estimate that there are 10 times more bacterial cells in your body than your own body’s cells, and new studies on bacteria in the gut indicate that your gut microbes might be influencing you more than you realize, having positive or negative effects on health, development, and possibly even personality and behavior. A recent study found that the average number of unique genes in gut bacteria, for a sample of 99 healthy European individuals, was 564 million, with a standard deviation of 122 million. Use the t-distribution to find and interpret a 95% confidence interval for the mean number of unique genes in gut bacteria for European individuals.