Elon Musk had a third child with an executive at Neuralink, his brain implant company. Musk and Neuralink Corp. director of special projects, Shivon Zilis, welcomed the baby earlier this year, Bloomberg News reported.

Neuralink didn’t immediately respond to a request for comment. In an interview with the New York Post, Musk confirmed the birth of his third child with Zilis, but did not disclose the child’s name or sex.

Musk told the Post that the birth of his latest child was not kept secret. “As for ‘secretly fathered,’ that is also false,” he told the publication. “All our friends and family know. Failure to issue a press release, which would be bizarre, does not mean ‘secret.'”

Musk and Zilis are already parents to twins born in 2021, shortly before the birth of Musk’s second child with musician Grimes, a baby girl named Exa Dark Sideræl Musk. Musk, the world’s second richest person, with a fortune valued at $207 billion, is a proponent of boosting the global birth rate, claiming in a 2022 tweet that a falloff in births is “the biggest danger civilization faces by far” — and adding that he is “doing my best to help the underpopulation crisis.”

“Many countries are already well below replacement rate, and the trend is that almost all will be,” Musk told the Post. “This is simply a fact, not a ‘debunked theory.'”

The world population has grown to about 8 billion today from 1 billion in about 1900, and is projected to hit 9 billion people by 2045. However, birth rates in some developed countries, ranging from South Korea to the U.S., have declined in recent decades — dipping below the replacement rate, or level at which a population replaces itself from one generation to the next, which is generally defined as 2.1 children per woman.

Declining birth rates in developed countries was recently flagged by the OECD as posing serious economic and social challenges, such as placing more financial strain on government services and pensions such as Social Security. Adults are having fewer children for a number of reasons, including a lack of affordable housing for families and the difficulties in managing both a career and family, the OECD said.

How many kids does Elon Musk have now?

The Tesla CEO has had six children with Canadian author Justine Wilson, who was married to Musk from 2000 to 2008. Their first child died of Sudden Infant Death Syndrome, or SIDS, when he was 10 weeks old, Wilson wrote in a Marie Claire article.

The couple later had twins, Griffin and Vivian, in 2004, followed by triplet in 2006, Kai, Saxon and Damian.

Musk also has three children with singer Grimes. Their first, named X Æ A-12, was born in March 2020; their second child, named Exa Dark Sideræl, was born in 2021. Their third child, named Techno Mechanicus, was born in 2023.

Musk has had three children with Zilis, including twins Strider and Azure. Earlier this year, he and Zilis welcomed their third child, whose name hasn’t been released to the public.

Who is Shivon Zilis?

Zilis, a Yale graduate, joined Neuralink in 2017, according to her LinkedIn page. In Walter Isaacson’s biography of Musk, she is described as Musk’s “intellectual companion on artificial intelligence since the founding of OpenAI.”

Zilis worked as an adviser to OpenAI from 2016 to 2019, according to LinkedIn, and served on the company’s board from 2020 to 2023. She’s also a fellow at the Creative Destruction Lab, which she describes in her bio as a machine-learning incubator at the University of Toronto.