Hmm, the subtitle says it includes "airborne microbes". Microbes can change, though, can't they? There are procedures like fecal transplants just to kick start

Hmm, the subtitle says it includes "airborne microbes". Microbes can change, though, can't they? There are procedures like fecal transplants just to kick start different microbe populations in a person. So it isn't all just an expression of their genes turning into physical traits, some of it is due to their history and what they were exposed to. Some antibiotic treatments, for example, could change your microbe population.