Elon Musk allegedly had twins with a Neuralink executive.

Elon Musk, the CEO of Tesla and SpaceX as well as the world's richest man, welcomed twins last year with an executive from one of his other companies, Neuralink, according to Business Insider on Wednesday. 

Musk, who quietly fathered the children with Shivon Zilis, who works for Musk at the company that hopes to develop an implantable computer chip for the human brain, according to documents obtained by Business Insider, who posted a tweet on May 24 saying "USA birth rate has been below min sustainable levels for 50 years."

The outlet obtained court documents pertaining to changing the children's legal names to include Musk's surname and Zilis' surname as part of the middle names. CNN Business was unable to independently confirm the contents of the documents, but according to a Travis County, Texas court docket obtained by CNN Business, the name change petition was initially filed in April 2022 and granted in early May — dates that correspond to the dates on the documents published by Business Insider. The court's stamp is on the documents, as is Musk's signature, and he is listed as the father and Zilis as the mother.

Musk did not immediately respond to requests for comment sent to Tesla, SpaceX, and Neuralink representatives.

According to her LinkedIn profile, Zilis' professional ties to Musk date back to at least April 2016, when she became an advisor to OpenAI. Elon Musk is a cofounder of OpenAI, a nonprofit research lab whose stated mission is to "ensure that artificial general intelligence benefits all of humanity." 

Musk held a live-streamed event in August 2020 to demonstrate the progress of Neuralink's technology, which it had implanted in a pig. Nearly a year later, Neuralink claimed that monkeys could play Pong after being implanted with the company's chips. However, Neuralink has recently been forced to address concerns about its testing practices. Denying allegations of animal cruelty while confirming earlier this year that monkeys died as a result of the testing. 

According to Zilis' LinkedIn, she began working for both Tesla and Neuralink in May 2017 and is now a director of operations and special projects at Neuralink. Zilis joined the OpenAI board of directors in 2020. Prior to joining Musk's companies, Zilis worked for a Bloomberg venture capital fund (where she was named to the Forbes 30 under 30 list for venture capital in 2015) and IBM. She has also served on the boards of at least two other AI-related organizations. Zilis did not respond immediately to a request for comment. 

This is the second set of twins Musk is thought to have fathered. Musk and his first wife, Justine, welcomed twins in 2004, followed by triplets two years later. (The couple, who were married from 2000 to 2008, lost their first child; Justine, an author, famously wrote for Marie Claire magazine in 2010 about what it was like to be married to and divorce Musk.) Musk went on to have two children with musician Claire Boucher, better known as Grimes. Their second child was born via surrogate in December 2021.