Elon Musk reportedly had twins with Shivon Zilis, an executive at Neuralink, one of his companies, in November.
The Insider report states that Zilis had the children weeks before Musk and his on/off partner Grimes, the musician born Claire Elise Boucher, had their second child, a daughter born via surrogacy, in December. The daughter, named Exa Dark Siderael Musk and known as Y, is a sister to X Æ A-12, 2, or "X AI Archangel", who is known as X for short.
While neither Musk, 51, nor Zilis, 36, have directly addressed claims that they have had twins, the Tesla founder has tweeted what seems to be a response to the allegations.
"Doing my best to help the underpopulation crisis. A collapsing birth rate is the biggest danger civilisation faces by far," Musk wrote on Thursday. "Mark my words, they are sadly true."
US television presenter Nick Cannon responded to Musk's tweet, writing: "Right there with you my Brother!"
Cannon, 41, has seven children and is currently expecting two more. He is father to twins Moroccan and Monroe, 11, who he had with his ex-wife, singer Mariah Carey. He also has two children with model Brittany Bell and twin sons with DJ Abby De La Rosa. He had a son named Zen with model Alyssa Scott, however, Zen died of brain cancer in December 2021, aged five months.
He is expecting a baby boy with model Bre Tiesi and another child with De La Rosa.
The birth of Musk and Zilis's twins came to light after court documents were filed to change their names so they would "have their father's last name and contain their mother's last name as part of their middle name", Insider reported.
Elon Musk's children
Including the twins, Musk has had 10 children.
Nevada, his first child with ex-wife Justine Wilson, died aged 10 weeks in 2002 of sudden infant death syndrome.
He and Wilson went on to have twins Griffin and Vivian in 2004, and triplets Kai, Saxon and Damian in 2006.
In April, one of Musk and Wilson's children filed to change her name in accordance with her new gender identity and to formally sever ties with her father. Vivian, 18, born Xavier Alexander, also sought to remove Musk from her full name, saying: “I no longer live with or wish to be related to my biological father in any way, shape or form.”