Bunions are a condition describing a noticeable bump at the base of the great toe. They can occur at any age from birth (congenital) through adulthood (acquired), but are more commonly a problem after the mid-thirties.  

Did I inherit this from my parent(s)?

Yes...and No.  You do inherit the type of feet your parent have, however, acquired bunions take time to develop through the years.  If you didn't walk, wear certain shoes or injure yourself then you may not get bunions.

How does a bunion form?

The formation of a bunion occurs as a result of a mechanical failure of the great toe joint to flex upward (dorsiflex).  The ability of the joint to dorsiflex is related to whether the arch of the foot remains stable while standing and walking.  If the arch does not support itself well during walking, then the joint becomes jammed or stiff.  For normal walking (versus tip-toeing) to occur the toe MUST dorsiflex while walking (Side note: try walking without flexing your great toe).  However, since it is difficult to naturally walk tip-toed the body compensates subconsciously by swinging the foot outward and walking around the stiff joint.   When the foot functions this way for long periods of time the joint eventually buckles and the buckling effect causes the metatarsal to protrude forming a bunion at the base of the Great Toe. 

Normal walking: note great toe can bend upwards. 

Great Toe Joint Stiff: Foot swings to the side because toe cant' bend upwards.

How do shoes affect bunions?

Shoes cannot actually cause a bunion. People who have rarely worn shoes (barefeet or sandal) do get bunions because the true cause is abnormal mechanics of the toe joint. Shoes, though, may accelerate the formation of it and contribute to the painful consequences.  

The edge of a shoe, combined with the large bump, can put pressure on the nerve under the skin leading to sharp pain and inflammation of the area.

This explains why wearing wider, larger or more accommodating shoes helps to relieve the pain of bunions.