Don't know which discussion on HN this was, but it was about the same book. Basically, each of us produces a varying amount of fat in our sweat and that leads t

Don't know which discussion on HN this was, but it was about the same book. Basically, each of us produces a varying amount of fat in our sweat and that leads to different bacterial biomes. The bacteria that metabolize the fat in the sweat are what actually produce the odors we recognize.