Hernias directly through the abdominal wall, when you haven't had a surgery or trauma to the area, are very rare.
Depending on where it is, a hernia
would have to go through several opposing layers of muscle or fascia. Hernias usually develop in natural weak points, like the inguinal or umbilical area. If you have a bulge anywhere on you abdomen and you cannot push it back in, see a doctor.
Answer assisted by Mike Moore, Medical Student