When the Oskiper triplets won the first-grade section of the National Scholastic K-12 Chess Championship in Florida earlier this month, it was a singular achievement, according to the United States Chess Federation, the game’s governing body.

In fact, chess-playing triplets are exceedingly rare. Mike Nolan, an official of the chess federation, searched its database, which has 747,000 current and past members, and found only 40 possible examples of triplets. Unsurprisingly, quadruplets were even rarer — only three. In an e-mail, Nolan said he found 2,600 possible groups of twins. (Nolan said the federation’s database is not exact as there may be some cases of duplicate ID’s or dates of birth that were entered incorrectly.)

Nolan wrote that among the groups of triplets or higher, there were only four where the rating — the measurement system used to rank players — exceeded 1,000, which is not very high. (An average federation member has a rating in the 1,500 to 1,600 range.) Constantine Oskiper’s rating after the national championship is 1,174, so he appears to be the highest rated triplet or higher to date.