Source code/machine code, I am just interchanging but in this analogy they are equivalent. Pre-natal influences change the epigenetics, i.e. "on" the genome. Th

Source code/machine code, I am just interchanging but in this analogy they are equivalent. Pre-natal influences change the epigenetics, i.e. "on" the genome. The structure of DNA is almost completely determined by histones, which are proteins that DNA wrap around, so once again, not the DNA. Microbiota affect the environment of the cells, meaning it is an input to the cell, not the source code. Any phages affecting the microbiota will affect the input to the cell. These factors aren't considered source code simply because it only affects the execution of the cell's source code.