A small receding chin is also known as a regressed or weak chin. Instead of protruding or lying flat, the receding chin is tilted back into the neck. This happens when the lower jaw or mandible is not aligned with the upper jaw.
Some people are born with a receding chin, and children often develop it as their bones grow. But over time, other people’s jaws can become weak. A pronounced bite may result in a weak jaw and jawline. Age is also possible. Over time, your jawline tends to become less pronounced and may even start to recede.