Crooked or crowded teeth occur when teeth erupt into the mouth and appear overlapped, angled, twisted or rotated. One of the most common signs of crowding in the upper teeth are instanding front teeth or canine teeth (i.e. the pointy teeth sitting outside and high). In the lower teeth, overlapping of the front teeth is most common.
It is generally true that crowding naturally worsens from a child to a teenager, as they shed baby teeth and adult teeth start to erupt. This is because the adult front teeth are wider than the baby teeth that they replace.