May 4 has been a day of celebration for Elon Musk, as his seventh child – son X – has turned four. 

"Lil X turns 4 today on May 4th," Elon shared with followers on his social media platform X, formerly known as Twitter, alongside a picture of the youngster sitting on what appeared to be a reception desk. Wearing blue denim jeans and a sweater, the toddler had a big smile on his face as he cheesed for the camera. 

X – real name X Æ A-12, pronounced "X Ash A Twelve" – is Elon's seventh child, and the oldest he has with former partner Grimes, real name Claire Elise Boucher. 

The pair later welcomed their daughter Exa Dark Sideræl with the help of a surrogate in December 2021; Exa goes by the nickname Y. 

Y's birth came a month after Elon became a father for the 10th and 11th time as he welcomed twins with tech executive Shivon Zilis. 

Grimes later explained her relationship with Elon, admitting to Vanity Fair that "there’s no real word for it". 

"I would probably refer to him as my boyfriend, but we’re very fluid. We live in separate houses. We’re best friends. We see each other all the time. We just have our own thing going on, and I don’t expect other people to understand it," she said. 

In March 2022 Grimes confirmed that they had split for good but they welcomed a third child, son Techno, in 2023; his birth was confirmed in a biography of the Tesla and SpaceX billionaire written by Walter Isaacson. 

Elon is also father to 19-year-old twins Vivian Jenna and Griffin, and triplets Kai, Damian, and Sax, who were born in 2006, with his first wife, Justine Wilson. Their eldest son, Nevada, tragically died at 10 weeks.

Elon is thought to have a strained relationship with daughter Vivian, after she petitioned the California court to recognize a new name and gender. Court documents posted online reveal that she asked for the changes due to "gender identity and the fact that I no longer live with or wish to be related to my biological father in any way, shape or form". 

Neuralink executive Shivon and Elon's twins, Strider and Azure, were born in Austin, Texas in 2021.

"Doing my best to help the underpopulation crisis. A collapsing birth rate is the biggest danger civilization faces by far," Elon wrote on the social media site X which he purchased in 2022. 

Shivon often shares videos of her twins on X, including in March 2024 when she revealed their first visit to an ice rink.

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