Thats where you get them from, mothers, lovers and pets. There's about 22 bacterium that live in the pockets, each being tied to a different condition, viz., arthritis, alzheimers, diabetes, atherosclerosis, cancer, and more. They're contagious, by kissing. They're cell wall-deficient anaerobes, and are relatively easy to kill. I got rid of mine about 4 years ago and haven't had a bad taste in my mouth since then, and my gums never bleed, even when provoked. Gum recession reversed also. This video is a good start, for those who have an interest