You might not instantly recognize Sean Lennon and James McCartney, but these two musicians are the offspring of rock royalty.

You might not instantly recognize Sean Lennon and James McCartney, but these two particular musicians broke the internet when they posed for a selfie together in the summer of 2018. And the reason? Both their fathers played in the biggest band in rock and roll history. Here’s a look at the pair’s iconic musical roots.

The Beatles came together in their Liverpool hometown at the turn of the 1960s. Just a few years later, Beatlemania took over the world, thanks to the guidance of manager Brian Epstein. Albums such as Rubber Soul, Revolver and Abbey Road then helped transform them from a pure pop act into highly credible and innovative rock and roll icons.

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The group split in 1970 but continued to be a significant inspiration for decades to come. Their worldwide sales tally stands at approximately 800 million, while they’ve also scored more U.K. number one L.P.s and U.S. chart-topping singles than any other artist. And each member enjoyed significant success with his solo career.

One of the band’s two main songwriters, John Lennon, recorded several classic L.P.s including Imagine and John Lennon/Plastic Ono Band. Alongside wife Yoko Ono, he also became just as renowned for his peace activism as his music. Tragically, shortly after releasing Double Fantasy in 1980, a gunman shot him fatally outside his Manhattan home at the age of just 40.

Lennon’s songwriting partner Paul McCartney decided to form another band with Denny Laine and first wife Linda in the wake of The Beatles’ split. Wings subsequently released one of the U.K.’s best-selling singles of all time, “Mull of Kintyre.” McCartney has also recorded more than a dozen solo efforts and has also become an outspoken advocate of animal rights.

Lead guitarist George Harrison also enjoyed success in a second group, The Traveling Wilburys, in the 1980s. Before that he’d achieved huge critical acclaim with 1970’s solo triple effort, All Things Must Pass, and founded both Dark Horse Records and HandMade Films. Sadly, the man known as “the quiet Beatle” passed away from lung cancer in 2001 at the age of 58.

Drummer Ringo Star also grabbed his opportunity to take the limelight with a series of hit solo records in the 1970s. His Liverpool accent later became familiar to a whole new generation as the narrator of children’s TV series Thomas and the Tank Engine. He’s continued to perform with various incarnations of his All-Starr Band since the late 1980s.

The four members of The Beatles had 10 biological children between them, many of whom have followed in their father’s creative footsteps. McCartney has three children from his first marriage to Linda; Mary, James and Stella. He also has a daughter, Beatrice, from his second, far more turbulent marriage to Heather Mills.

Lennon also had children from different marriages: Julian with his first wife, Cynthia, and Sean with his second, Yono. Starr has three sons – Zak, Jason and Lee from his first marriage to Maureen Cox – while Harrison was survived by his wife Olivia and son Dhani. But it was two particular Beatles offspring who sent the online world into a frenzy in 2018.

Indeed, fans of the Fab Four got all in a tizz when Sean Lennon and James McCartney posed for a selfie uploaded to Instagram. And judging by the sight of an acoustic guitar, the sons of John and Paul appeared to be in the middle of making music together. Of course, both men are no stranger to the studio or the stage.

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In fact, Sean Lennon made his recording debut aged just five when he narrated a tale for Yoko Ono’s Season of Glass L.P. He continued to work with his mother throughout his teens before releasing his first solo album, Into the Sun, in 1998. He followed it up eight years later with Friendly Fire.

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Lennon has also been a prolific collaborator over the years. He’s produced material for Lana Del Rey, Soulfly and Irina Lazareanu, and written film scores for Rosencrantz and Guildenstern Are Undead, Tea Fight and Alter Egos. He also teamed up with Les Claypool from Primus to form The Claypool Lennon Delirium and with partner Charlotte Kemp Muhl in The Ghost of a Saber Tooth Tiger.

James McCartney has also contributed to several of his parents’ records. He appeared on his father’s solo efforts, Flaming Pie and Driving Rain, and his late mother’s 1998 release, Wide Prairie. He then became an artist in his own right in 2010 with the Available Light E.P.

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After releasing a second E.P., Close at Hand, shortly afterwards, McCartney issued his full-length debut album, the simply-titled Me, in 2013. After a U.S. tour, sophomore collection The Blackberry Train arrived three years later. In a 2012 interview with the BBC, McCartney teased fans with the prospect of a “next-generation” Beatles, featuring himself, Sean Lennon, Dhani Harrison and Zak Starkey.

Sadly, this 2.0 version of The Beatles failed to materialize. However, James McCartney does appear determined to collaborate with several Fab Four offspring. In 2016 he recruited Dhani Harrison to serve as guitarist and backing vocalist on his single, “Too Hard.”

And then there’s the aforementioned Instagram photo with Sean Lennon. Indeed, the fact that McCartney was holding an acoustic guitar has led many to believe that a new Beatles-adjacent collab could be on the way. But with a simple caption of “Peekaboo,” the pair weren’t giving anything else away.

Of course, this isn’t the first time that Lennon has been pictured with the offspring of another Beatle. In 2017 he was snapped alongside Paul McCartney’s fashion designer daughter Stella at New York Harlem’s Cotton Club. Stella was visiting the Big Apple to work on her pre-fall, star-studded fashion show.

And in May 2018 Lennon was pictured cruising along the Thames with George Harrison’s son Dhani. The former had traveled to the U.K. to help open an exhibition about his famous parents at the Museum of Liverpool. Yoko Ono herself treated those attending the premiere of Double Fantasy – John and Yoko to a visit.

We might have to wait to find out whether the next-generation Lennon and McCartney have been making music together. But new Beatles-related music came in 2018 with the release of Paul McCartney’s first solo album in five years. Named after one of his very own paintings, Egypt Station was produced by hitmakers Greg Kurstin and Ryan Tedder.

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Several months previously, the original McCartney-Lennon partnership also made headlines once again. That’s when its surviving member appeared at New York City’s March for Our Lives. Sporting a “We Can End Gun Violence” shirt, McCartney paid tribute to his late bandmate at the event. He said, “One of my best friends was killed by gun violence right around here, so it’s important to me.”