Claw toes, collapsed arches, corns, bunions and spur heels are just some of the problems badly fitting shoes can cause.
Emma Supple is a foot doctor, called a podiatrist, who's treated loads of children with foot problems.
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She said because children's feet are still growing, if they wear poorly fitted shoes their feet can start to take the shape of those shoes.
She added: "If you wear bad shoes through your childhood, and your toes and your foot starts to change shape, then your knees will change and your hips will change and you'll start to develop problems other than your feet."