Elon Musk had twins with one of his company’s executives last year. Musk welcomed twins with Neuralink’s Shivon Zilis in 2021, bringing his child tally up to nine known children, according to court documents obtained by Insider.

In April, the Tesla CEO and Zilis filed a petition to change the two children’s names to “have their father’s last name and contain their mother’s last name as part of their middle name,” according to the outlet.

The two babies arrived just before he and Grimes had a child via surrogate in December. The mother of the twins currently works as director of operations and special projects for Neuralink, where Musk is co-CEO.

The news about the richest man alive’s two children comes days after his 18-year-old child Vivian Jenna Wilson was granted a name and gender change in California, removing “Musk” from her legal name and selecting a first name reflective of her gender identity.

Wilson told the court she wanted the name change due to “the fact that I no longer live with or wish to be related to my biological father [Musk] in any way, shape or form,” NBC reports.

Last month, the Tesla CEO was accused of exposing his penis to a flight attendant for SpaceX, his aerospace company, during a flight. The attendant was paid $250,000 to settle the case in 2018.

In March, Grimes revealed she had welcomed a second baby with Musk, named Exa Dark Sideræl. They call her “Y,” following her older brother nicknamed “X.”

Asked by Vanity Fair whether the two were still “together,” Grimes said at the time, “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.”

Grimes added that they planned on having more kids as well. “We’ve always wanted at least three or four,” she said.

She later sent out a series of tweets stating that the two had broken up, but that Musk was still “the love of my life.”

According to Insider, Musk and Amber Heard, who briefly dated in 2016, may also have frozen embryos together. During the Depp-Heard trial, the boss of Heard’s sister testified that she heard from Heard’s mother that the actress was “in a legal battle with him over the rights to embryos they had created together.” She added: “He wanted to destroy them, and Amber tried to keep them to have a baby.”

Perhaps Musk’s next mission isn’t heading to space, but shooting babies out to singlehandedly change the United States fertility rate: After all, he has a chart of the country’s falling birth rate pinned to his Twitter profile. “USA birth rate has been below min sustainable levels for ~50 years,” reads the tweet.