Genetics and certain health conditions can cause someone to have flat feet. Experts explain when it can become a problem. Most people don’t spend too much time thinking about the arch of their foot — how high it is, how low it is — that is, until foot or ankle pain becomes a problem. The foot is supposed to have an arch; it helps support your body’s alignment, protects the foot from shock and helps you walk on uneven surfaces . But roughly 25% of adults have flat feet, said Dr. Jesse N.