Bunions are one of the most common foot problems. They often run in families, which suggests that the inherited shape of the foot may predispose people to them.
Pronated feet (flatfeet) are unstable and often cause bunions. Body weight is repeatedly transferred to the hallux while walking, and in flat feet, this transfer of weight allows certain muscles to become stronger than others. This overpowering of muscles causes the toe to bend and deform.
Bunions may be caused by tight, pointy-toed, or high-heeled shoes, and shoes that are too small. Women get bunions much more often than men. Improper shoes exacerbate the underlying cause of unstable flatfeet.