Flat feet usually stem from genetics, incomplete arch development in childhood, or an arch that collapses later in life.
Wondering why you have flat feet comes down to one key question: have your arches always been low, or did they flatten recently? The answer matters because lifelong flat feet are usually a normal foot shape, while new arch collapse in adulthood often signals a treatable problem like tendon damage. Either way, most flat feet cause zero symptoms and need no treatment at all.
The Main Reason Flat Feet Develop
Flat feet, medically called pes planus, develop through one of two pathways. Either the arch never formed in the first place, or a normal arch collapsed later from injury, aging, or an underlying condition.
For many people, flat feet are simply inherited. The condition runs in families, and some people are born with naturally low or absent arches that stay that way for life. This is a structural trait, not a disease. Cleveland Clinic notes that flat feet can be linked to genetics or congenital differences in how the foot bones fit together.
Children often look flat-footed because their arches haven’t finished forming. Infants and toddlers typically have flat feet, with arches developing gradually through childhood as muscles and ligaments strengthen.
When Arches Collapse In Adulthood
If your arches were normal and then flattened, the most common culprit is posterior tibial tendon dysfunction, or PTTD. That tendon runs down the inside of your ankle and holds the arch up. When it becomes inflamed, overused, weakened, or torn, the arch loses its support and drops.
Several other factors can drive adult-acquired flatfoot:
- Foot or ankle injuries, including fractures and ligament damage
- Aging and years of wear-and-tear on the joints
- Arthritis, especially rheumatoid arthritis
- Diabetes-related nerve damage, which can lead to Charcot foot, a serious bone condition
- Obesity, which adds extra load to the arch’s supporting structures
Tight Achilles tendons can also contribute to lifelong flat feet by pulling the foot into a flattened position. Pregnancy is sometimes listed as a contributing factor, though major health authorities don’t emphasize it as a primary cause.
Are Flat Feet A Problem?
For most people, flat feet are painless and never cause trouble. You can walk, run, and live normally without treatment. Many people with flat feet never realize they have a “condition” until a doctor points it out.
Flat feet only need attention when symptoms appear. Possible signs include foot pain, fatigue after standing or walking, instability, or changes in the way you walk. When the arch collapses suddenly in adulthood, that’s worth a medical evaluation, especially if you notice swelling, pain along the inside of the ankle, or a foot that’s getting flatter over time.
Rapid arch collapse in one foot with pain and swelling could point to PTTD or, in people with diabetes, Charcot foot. Both need prompt care, as adult-acquired flatfoot can reflect progressive tendon or bone damage.
| Cause | When It Happens | What To Know |
|---|---|---|
| Genetics / inheritance | From birth | Normal foot shape for many people |
| Normal childhood development | Infancy through childhood | Arches usually form on their own |
| Posterior tibial tendon dysfunction | Adulthood | Most common cause of adult arch collapse |
| Injury or fracture | Adulthood | Foot or ankle trauma can drop the arch |
| Arthritis | Adulthood | Rheumatoid arthritis is a known risk |
| Diabetes / Charcot foot | Adulthood | Serious complication needing prompt care |
| Tight Achilles tendon | Lifelong | Can contribute to persistent flat feet |
Risk factors that increase your chances of flat feet include obesity, diabetes, foot injuries, rheumatoid arthritis, aging, and a family history of the condition. If new flattening appears alongside severe pain or trouble walking, the cause may be more than a normal variation.
If arch pain or fatigue is slowing you down, supportive footwear makes a real difference. Finding the right pair starts with knowing your foot’s needs — our guide to the best women’s shoes for flat feet breaks down tested options that provide the arch support most flat-footed walkers need. Mayo Clinic’s overview of flatfeet and Cleveland Clinic’s page on pes planus both emphasize that supportive shoes and orthotics are typical first-line responses when symptoms appear.
The bottom line: flat feet are rarely a medical problem. They’re either the shape you were born with or the result of a tendon or joint issue that developed later. If they don’t hurt, they don’t need fixing. If they do, see a doctor — and Mayo Clinic’s flatfeet overview explains the treatment options available.
FAQs
Can shoes cause flat feet?
Footwear alone doesn’t typically cause flat feet. The condition comes from genetics, development, or arch collapse from tendon dysfunction, injury, or arthritis. Wearing unsupportive shoes can make symptoms worse, but it isn’t a root cause according to major health sources.
Do flat feet get worse with age?
They can. Aging brings wear-and-tear on tendons and joints, and the posterior tibial tendon weakens over time. That’s why arch collapse is more common in adults than children. Regular foot pain or visible flattening later in life warrants a medical check.
Are flat feet a disability?
No. Flat feet are a normal foot variation for many people and typically don’t count as a disability. They only become a concern when they cause persistent pain, limit walking, or stem from a progressive condition like tendon dysfunction or Charcot foot.
References & Sources
- Cleveland Clinic. “Flat Feet (Pes Planus).” Details causes, risk factors, and when flat feet require treatment.
- Mayo Clinic. “Flatfeet.” Explains symptoms, causes, and treatment approaches for flat feet.
- NHS. “Flat Feet.” Outlines normal arch development and when flat feet signal a problem.