The human gut is home to trillions of microbes that serve beneficial purposes. However my recent research has shown that the wrong mix of ‘normal’ microbes can be detrimental to health. In this research I will investigate how variation in the human genome relates to variation in the diversity and functions of microbes in the gut. My lab will investigate how (1) gene sequence variation and (2) gene copy number variation impact microbial diversity and function in the gut. To investigate gene sequence variation, I will make use of a population of previously genotypes twins: comparing their microbiomes will allow me to identify human genes that co-vary with their gut microbiotas. In a second approach, I will target specific genes, such as the human amylase gene, that varies in copy number and that I predict impacts the microbiome. I employ a combination of high throughput sequencing technologies to identify genes of interest to follow up with experimental work.