From the most common birthday to the surprising origins of Happy Birthday — ten genuinely surprising facts about birthdays most people don't know.
The most common birthday in the United States falls on September 9th, and the pattern holds in most countries with similar cultural backgrounds. The reason is straightforwardly mathematical: count back nine months from September and you arrive at December, specifically the holiday period between Christmas and New Year when, statistically, couples spend more time together at home. Birth rates in September and October are consistently higher than any other month in the Northern Hemisphere, which means that if you share your birthday with many people you know, there is a reasonable chance you were all conceived during a period of festive togetherness.
The song Happy Birthday to You was claimed as copyrighted material by Warner Music Group and the company collected licensing fees for its use in films, television programmes and public performances for decades, earning an estimated two million dollars annually. In 2016 a federal judge ruled that the copyright claim was invalid because the original 1893 composition to which the lyrics were added had always been in the public domain. The ruling meant that restaurants, filmmakers and broadcasters who had been paying licensing fees for years had in fact been paying for something nobody owned. Happy Birthday is now definitively free to sing, film and broadcast without cost or permission.
People born on February 29th, known as leaplings or leap year babies, make up approximately 0.07 percent of the world's population, meaning there are around five million leaplings alive today. The question of when they celebrate their birthday in non-leap years is handled differently across cultures and legal systems: the United Kingdom legally recognises March 1st as the birthday for official purposes, while the United States and several other countries use February 28th. Most leaplings develop a cheerful flexibility about the whole matter, celebrating on whichever nearby date suits the occasion, and many take pride in technically being far younger in birthday count than their calendar age.
Thailand's Songkran festival, held each April to celebrate the Thai New Year, has become in effect a nationwide birthday celebration lasting up to five days in which the entire country participates. The festival involves the world's largest water fight, with participants drenching strangers, friends, monks and occasionally police officers with water pistols, buckets and hoses in a ritual that symbolises washing away the previous year's misfortunes. Visiting foreigners are neither excluded from the water fights nor warned with sufficient firmness about their inevitability, which means that every year thousands of tourists discover that no amount of luggage wrap can protect a passport from Songkran.
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