Although shoes which have a narrow toe box and pointed end crunch the toes together, it is certainly not the main cause of a bunion.  Men and women who have a bunion deformity are predisposed towards bunions due to their genetics which dictates a particular foot structure that causes the bunion to form over time. Bunions are most often a result of an overly pronated foot structure and instability of a joint in the foot that is near the arch.