Second, they make it easier for you to pick up tiny things, like loose threads. They also come in handy when you have an itch that needs scratching. When you feast on your fingernails, you take away your fingertips' protection force. That means you may leave your fingertips open to infections. Also, biting your nails usually means that the skin around them gets irritated and can become easily infected.
Some kids even chow down on their nails until their fingertips and cuticles bleed.
It's not a pretty sight and it invites germs to move in, which can cause an icky infection. Think about all the stuff you touch all day long, like your baby sister's drool-dripping pacifier, your stinky gym socks, or slimy earthworms for your science project. When the germs from these things hang out around and under your nails and you bite them, the germs catch a free ride inside your body. The other thing that makes biting a bummer is that you have to hold your hand in front of your face to do it. It's also hard to smile or talk to pals when you're nibbling on your nails.