Bunions, or bumps on the inside of the great toe joint, form for many reasons.  It is important to remember that it is not just extra bone forming, but rather the long bone behind your great toe joint leaning out and the toe moving over in response to it.  It can happen when we have abnormal motion at the back of the foot, which affects a muscle that stabilizes the bones that make up the great toe joint.  There also is a familial component.  If mom or grandma had bunions, you probably will too!  It's why we always recommend getting your children's feet checked if you have a bunion because if we can slow the progression you may be able to prevent surgery.