The big toe deformity Hallux valgus is commonly called "a bunion".
A bony lump appears on the inside of the foot, and the toe tilts towards the smaller toes. As the toe leans out of place, the bony bump of the "knuckle-bone" of the big toe becomes exposed and sometimes has a soft fluid swelling.
Some of the causes of bunions are not preventable. These include the way your bones have developed, the laxity of your ligaments, the spasticity of your muscles and the genes you have inherited. Tight fitting shoes can also contribute towards the formation of bunions.
Just because you have bunions does not mean your children will have them, but they do tend to run in the family. Bunions are commoner in people with unusually flexible joints, and that may be the heredity connection. Women also seem to have more instances than men.
Shoes? - Cultures who don't tend to wear shoes still have instances of bunions, but not as many. Squeezing your toes into poorly fitting shoes may worsen the deformity, particularly in higher-risk groups.
Wide well-fitting shoes together with a pad for the bony protrusion are generally sufficient for most people. Avoid high-heals as they tend to push the foot forward towards the toes.
An operation involves correcting the deformity of the big toe resulting in a narrowing of the foot towards a better shape, but this will not deliver an entirely regular foot.