Often they’re caused by hyper-pronation of the feet, where you roll slightly onto the inside of the sole of the foot as you walk, giving certain tendons a mechanical advantage over others. Ligament laxity, where the ligaments are too loose to keep the bones and joints in proper alignment in your feet, makes you prone to bunions. Similarly, during pregnancy, when hormones relax all your ligaments, a bunion may form. When the bones get out of alignment, for whatever reason, trouble starts.