Genetic factors play a significant role in whether a child has crooked teeth. For instance, if a baby inherits large teeth from one parent and a small jaw from the other, it will understandably lead to overcrowding in the mouth when the primary teeth emerge. This set of factors often results in crooked teeth and the associated problems.
Misalignment of the teeth can also result from an infant who is in the habit of putting his or her fingers into the mouth, like when sucking the thumb. Sucking the thumb puts pressure on both the upper and lower teeth while the thumb is being sucked and causes overcrowding in the mouth as the teeth develop. Less frequently, an overcrowded mouth can result from extra teeth.