Who are Elon Musk's children? The names and bios of his kids and their mothers

• Tesla CEO Elon Musk has 10 known children with 3 different mothers.
• The world's richest individual has said the biggest threat facing the world was a flatlining birthrate.
• Here's a look at Musk's family. 

Tesla CEO Elon Musk, who's said that he's "doing his best to help the under population crisis," has long been sounding the alarm on a potential population collapse — a problem he has said is a bigger risk to civilization than global warming. 

Here's a look at his family. 

How many biological children does Elon Musk have?

Elon Musk has ten known children with three different partners.

Musk's first wife, the author Justine Musk, told Musk's biographer, Ashlee Vance, that he "wanted to get married and have kids early on." In 2002, the couple had their first child, Nevada Alexander Musk, who died of sudden infant death syndrome at just 10 weeks. After the baby's death, the couple turned to in vitro fertilization. Justine gave birth to twins, Vivian and Griffin, in 2004, then triplets, Kai, Saxon, and Damian, in 2006.

In 2022, Vivian was granted approval to legally change her name and gender. In her petition, she wrote that she no longer wished "to be related to my biological father in any way."

Musk and Grimes were romantically linked in 2018. Grimes gave birth to their first child, X Æ A-Xii Musk, in 2020. The existence of their second child, a daughter named Exa Dark Sideræl Musk, was revealed in March of 2022 when Exa started crying while Grimes was being interviewed by a Vanity Fair reporter. Exa's name was later changed to "Y" or "why," the singer said on Twitter in March of this year — or just "?," though Grimes said "the government won't recognize that."

The couple also has a third child, a son named Techno Mechanicus, who was born mid-June in 2022. Musk and Grimes kept his existence a secret too until the recent release of a new biography of Musk by author Walter Isaacson. Techno Mechanicus goes by the nickname Tau, a hint at Musk's own birthday — the Greek letter stands for the number equal to two times pi, which rounds to 6.28. While their daughter Y was born through a surrogate, it's unclear how Tau was conceived or born.

Insider also revealed that Musk had twins quietly in November 2021 with one of his top executives, Shivon Zilis. Their names have not been revealed publicly. 

The world's richest individual has said the biggest threat facing the world was a flatlining birthrate and claimed that overpopulation was a myth.

The SpaceX CEO wants to put humans in a settlement on Mars. He previously said on a podcast that SpaceX will put humans on the planet with its Starship rockets in five to 10 years.

However, he claimed there would not be enough people to move to Mars if the demographic crisis continued.

How do you pronounce the names of Musk's son with Grimes?

Musk and Grimes originally had named their son X Æ A-12 but had to change it to X Æ A-Xii following a violation of California's naming laws.

Grimes broke down the significance of each letter of the bizarre name on Twitter, explaining that X stands for "the unknown variable," Æ stands for "my elven spelling of Ai," and A-12 is the "precursor to SR-17 (our favorite aircraft)."

Grimes later clarified in an Instagram comment: "It's just X, like the letter X. Then A.I. Like how you said the letter A then I." Musk used a conflicting pronunciation, saying on the "Joe Rogan Experience" that the Æ is pronounced "ash." 

While it's still not clear how the latter half of the name is pronounced, it appears that Musk and Grimes are keeping it simple day-to-day and simply calling the baby X.

Did Musk use IVF to conceive his children?

Yes, Musk used IVF to conceive five of his children with his first wife Justine, as were Musk's twins he had last year with his Neuralink employee, Shivon Zilis. His second child with Grimes was born through a surrogate.