Over the past two years, he has become increasingly fixated on what he sees as another threat: declining birthrates. He believes a global population collapse is coming that will wipe out humanity. His apocalyptic vision is unlikely, according to demographers, but on X, the social media company he owns, he has been encouraging followers to have as many children as possible.

“It should be considered a national emergency to have kids,” Musk posted in June.

For the moment, Musk is temporarily encamped in Pennsylvania, immersed in the presidential campaign and spending tens of millions of dollars to finance Trump’s get-out-the-vote operations.

But it is in Texas where Musk has moved much of his business operations and is trying to establish his family compound. The compound is off to a bumpy start.

One of the mothers, Shivon Zilis, an executive at Neuralink, Musk’s brain technology startup, has moved into one of the homes with her children. But Claire Boucher, the musician better known as Grimes, who is the mother to three of his children, is in a protracted legal fight with Musk and has so far steered clear.

The third mother is Musk’s first wife, Justine Musk, with whom he has five living children, all in their late teens or older. There is room in the Austin compound if they were to visit, though he is estranged from at least one of those children.

In choosing Senator J.D. Vance as his running mate, Trump brought declining birthrates to the forefront of this year’s presidential election. Vance, who has raised alarms about the issue, made headlines for scolding “childless cat ladies.”

In a biography published in 2015, Musk worried that educated people weren’t having enough children. “I’m not saying like only smart people should have kids. I’m just saying that smart people should have kids as well,” he said. “I notice that a lot of really smart women have zero or one kid. You’re like, ‘Wow, that’s probably not good.’”

Musk, his attorney and the head of his family office did not return requests for comment. Representatives for Boucher did not return requests for comment. Zilis and Shanahan also did not return requests for comment.

All Musk’s children

Elon Musk and his first wife, Justine Musk, had their first child, a boy named Nevada, in 2002, two years after they married. The child died unexpectedly in infancy.

The couple had five children using IVF before they divorced in 2008: twins Griffin and Vivian, who are now 20, followed by triplets Saxon, Damian and Kai, now in their late teens. Elon Musk has said that IVF is a more efficient way of having children because it allows parents to control parts of the process, according to a person who understands his thinking.

By 2016, as the head of Tesla and SpaceX, Musk had amassed a net worth of more than $US11 billion, according to Forbes. That year, he warned for the first time on Twitter, the social network now known as X, that the world could be headed for population collapse.

“Consequences of population implosion greatly underestimated,” he wrote in response to an article about falling birthrates.

He twice married and divorced actress Talulah Riley, whose desire to focus on her career instead of having children was a factor in their breakup, according to three people familiar with her thinking. Representatives for Riley didn’t return requests for comment.

In 2020, Musk and Boucher, whom he started dating two years earlier, had their first child, a son they named X Æ A-Xii, or X for short.

Over the next few years, Musk had more children with Boucher as well as with Zilis.

Musk has offered to share his DNA. At a dinner party held at the home of a well-known Silicon Valley executive last year, Musk offered to provide his sperm to a married couple he had met socially only a handful of times, according to two people who were present for the interaction.

The couple had mentioned at the dinner that they were having trouble conceiving a child. Musk told them he was happy to assist, and boasted about his many children, according to the people present.

The compound

Initially, Musk had hoped to build a compound for his families on hundreds of acres that he and his companies owned outside Austin, near Tesla’s headquarters, according to four people familiar with the plans. But that idea appeared to fall apart after the Justice Department began investigating whether Tesla’s resources had been used on a secret effort to build a glass house for Musk’s personal use, according to The Wall Street Journal.

In August 2023, Musk said he was “not building a house of any kind”, in a post on X.

By that time, Musk had begun touring Austin for homes that could fit his growing families but was having trouble with at least one of the mothers of his children.

He had been living with Boucher in a 6900-square-foot (641-square-metre) house on a small cul-de-sac, according to three people familiar with the couple, when the pair welcomed a third child, a son born via surrogate.

Musk wanted to buy property next to the one he lived in with Boucher so he could create a private compound and incorporate more of his children.

But Boucher, who once described her relationship with Musk as “very fluid”, moved out in the summer of 2023. She eventually left Austin amid a custody battle with Musk, according to three people familiar with her move.

Still Musk continued his home purchase spree.

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It’s unclear which members of Musk’s families will live in those homes. Some of his oldest children aren’t close to their father, including his daughter Vivian, who is transgender. In an interview, Musk said Vivian was “dead, killed by the woke mind virus”. Vivian, for her part, accused Musk of pretending to care about his children. “You are not a family man,” she wrote on Threads in August. She declined to comment.

Only Zilis is now living in Austin, where she is sometimes seen at events around the city, three people familiar with her said. In June, Musk confirmed to The New York Post that he had a third child with Zilis after Bloomberg reported on the child’s existence.

In September, pop star Taylor Swift endorsed Kamala Harris for president, signing her Instagram post “Childless Cat Lady”. Musk posted on X, “Fine Taylor…you win…I will give you a child and guard your cats with my life.”

People close to Musk believe he was only half joking.