These six songs are about as beloved and recognizable as they come. But did you know that every single one uses a borrowed melody?

1. "My Country ‘tis Of Thee"

This patriotic ode to good ole Uncle Sam copies Britain’s national anthem. In 1832, future minister Samuel Francis Smith wrote the lyrics to My Country ‘tis Of Thee while studying at Andover Theological Seminary. What he didn’t write, however, was its musical accompaniment. Note for note, this was taken from a swelling German hymn entitled "God Bless Our Native Land." But not even that song’s melody was original: It previously appeared in "God Save the King/Queen," which dates back to (at least) 1745. And some historians aren’t even convinced that was original; it might just be an adaptation of a tune that dates back to the seventeenth century.

2. "For He’s a Jolly Good Fellow"

"For He’s a Jolly Good Fellow" has a morbid backstory. In 1709, the first Duke of Marlborough John Churchill led British forces to a bloody, costly victory over the French and Spanish at the Battle of Malplaquet. Afterward, there were whispers that Churchill died amidst this carnage. He hadn’t, but detractors spat on his nonexistent grave anyway. Enter "Malbrough s’en va-t-en guerre" (“Marlborough is Going to War”), a lively ballad in which Churchill not only perishes but is buried, mourned, and ascends to heaven. 

Eventually, "Malbrough s’en va-t-en guerre" spread and begat several imitators set to the same tune. Among these, "For He’s a Jolly Good Fellow" is easily the most famous.

3. "Twinkle, Twinkle Little Star"

Stand up and sing this one out loud. Wasn’t that fun? OK, now sing that alphabet song everybody learns in kindergarten. Notice any similarities? Both are based on a popular French lullaby called "Ah! Vous Dirai-Je, Maman" or "Shall I Tell You, Mother?" Basically, it’s about a kid with a really big sweet tooth:  

The simple tune found a fan in Wolfgang Amadeus Mozart, who helped make it famous by composing a piece that played 12 variations back-to-back. Originally, "Twinkle, Twinkle Little Star" had nothing to do with any of them; it started out as a nursery poem written by Jane Taylor in 1806. Someone—we’re not sure who—later came along and paired Taylor’s words with the Gallic tune.

4. "What Child is This?"

William Chatterton Dix wrote a poem called "The Manger Throne" in 1865. Six years later, a modified version of his poem found its way into a book of carols with a melody that had been hummed around England for centuries. Shakespeare even referenced it: The Merry Wives of Windsor (1602) stars a pompous knight named Sir John Falstaff who, at one point, shouts “Let the sky rain potatoes! Let it thunder to the tune of 'Greensleeves!'”

A hymn for lovelorn dreamers, "Greensleeves" tells the story of a fair maiden and the suitor whose heart she’s broken. King Henry VIII is said to have composed it after his future wife Anne Boleyn rejected some early advances, though most historians dispute that story.

5. "The Star-Spangled Banner"

You may have heard that America’s national anthem is based on a British drinking shanty, which isn’t entirely true. Francis Scott Key’s masterpiece was actually inspired by the theme song of a respectable U.K. gentleman’s club. In 1814, musically-inclined, well-to-do Londoners gravitated towards the Anacretonic Society, which often kicked off meetings by singing this:

Lyrical highlights include “The Yellow Hair'd God and his Nine Fusty Maids/From Helicon's Banks will Incontinent Flee!” How catchy!

6. "Happy Birthday to You"

According to Guinness World Records, this is the most famous song in the English language. And, depending on who you ask, it might have also been the product of self-plagiarism. Kentucky sisters Mildred and Patty Hill published the charming tune in 1893. Called "Good Morning to All," it initially went as follows:

Good morning to you

Good morning to you

Good morning, dear children

Good morning to you.

“[Mildred] was the musician,” Patty, a kindergarten teacher whose students used to love singing this song, said, “and I was, if it is not using too pretentious a word, the poetess.” At some point, however, her poetic words were replaced. By 1935, "Happy Birthday to You" had evolved from the Hills’ ditty. But do these sisters deserve credit for that song, too? Or did a complete stranger come up with it? Opinions differ.

But if you’re planning on singing "Happy Birthday to You" anytime soon, proceed with caution. As the cast of Aaron Sorkin’s "Sports Night" found out, it’s copyrighted: