Nails are formed within nail beds that is a skin lying beneath them. Nail-biting would not affect the normal growth of nails as long as this nail bed remains intact. However, when the fingernail separates from the nail bed, the growth would probably stop. The nail disorder you get due to this is called Onycholysis. It starts from the tip of the nail and progresses back. It is important to have healthy nails. Strong nails indicate good health. Although, there are a lot of causes due to which they become dry, thin and brittle.