Science sides with your mom. Your immune health has much more to do with which bacteria survive in which proportions than with your fear of exposure, because it

Science sides with your mom. Your immune health has much more to do with which bacteria survive in which proportions than with your fear of exposure, because it's incredibly unlikely that you've never been exposed to those species. You were probably born with them and so was baby. If your saliva is well formulated, they are in a healthy balance and you're fine. If not, you might have some bad genes because you're not making good saliva. Floss and brush, and get regular cleanings.