Most people have 20 of these, but in 1921 a boy born in England had 29 of them. What were they?

The typical human blueprint calls for twenty digits in total, but the condition of being born with more is a surprisingly common variation. Known medically as polydactyly, this trait comes from the Greek words for "many" (poly) and "digit" (dactylos). It's one of the most frequent congenital limb anomalies and occurs when a single digit on the hand or foot splits during fetal development, creating an extra one. This can range from a small, non-functional nub of skin to a fully formed and working finger or toe.

The English boy born in 1921 is a famous and extreme example of this condition. He was documented as having a total of 29 digits: fifteen fully-formed fingers and fourteen toes. While his case is exceptionally rare, polydactyly itself occurs in about 1 in every 500 to 1,000 births. In many instances, the extra digits are simply tied off or surgically removed shortly after birth for practical and cosmetic reasons, which is why the trait is not more commonly seen in the adult population.