Polydactyly is when an individual is born with extra digits, it occurs in 1 in 500 births and is most common to have an extra toe on the outside of the foot.
Polydactyly is most common in African-American demographics; it is the failure of differentiation in the apical ectodermal ridge during pregnancy in the 1st trimester. It is usually genetic as it is autosomal dominant showing there is a family history.
It can cause an issue with shoe fitting, and in some cases pain due to extra pressure.
Treatment can be conservative through observation, proper footwear, in some cases special shoes will need to be made to accommodate the size of the foot. Alternately, surgery may be required to remove the extra digit, this is done best at an early age between the ages of 9-12 months.
Reference:
https://www.orthobullets.com/pediatrics/4078/polydactyly-of-foot
http://www.footvitals.com/wp-content/uploads/2014/03/29_Polydactyly-300×252.jpg
