Sure! I am engaged in related work. Every day, tens of thousands of cells in the human intestine naturally fall off and enter the intestine. Some of these cells will degrade, and some will be excreted with feces. There are many commercial kits for extracting fecal DNA, from which DNA can be extracted for the detection of intestinal diseases. Because the detection of diseases are all abnormal genes, the number is very small, so it is quite easy to extract the DNA of normal people, which can be completed only by a few grams of feces. It is more prone to internal bleeding such as hemorrhoids, which will increase the number of human genomes in feces. As for the interference of other DNA, the current technology can completely eliminate it and get complete human genome information.