A former OpenAI board member has explained how her unconventional personal relationship with Elon Musk evolved into a relationship with four of his children.

Shivon Zilis testified in a federal courtroom in Oakland, California, for hours on Wednesday as part of Musk's lawsuit trying to reverse OpenAI's change to a for-profit company.

The focus of Zilis's appearance was her direct involvement in early talks with Musk about the company becoming for-profit, as well as her work for and involvement with Musk while advising OpenAI.

"I still really wanted to be a mum, and Elon made the offer around that time, and I accepted," she said, explaining Musk in 2020 had offered to donate sperm.

"He was encouraging everyone around him at that time to have kids, and he'd noticed I did not. He offered to make a donation," Zilis said.

Zilis has worked as a venture capitalist in Silicon Valley for over 15 years and held executive positions at Musk's car company, Tesla, and his neurotechnology firm Neuralink.

She joined OpenAI as an advisor in 2016, not long after it was founded, and said on Wednesday that it was through that position that she first met Musk.

Given Zilis's role across Musk's companies and OpenAI, and her eventual service as a director at OpenAI from 2020 to 2023, she is an important witness in the trial.

OpenAI lawyers have suggested that she funnelled information about OpenAI to Musk after he left the AI company in 2018, which he co-founded and to which he made early donations.

Zilis said she had a "one-off" romance with Musk about a decade ago but was not romantically involved with Musk in 2020, when Musk initially made the offer to father her children.

She explained she had been struggling with certain health issues, which had changed her initial plans to follow a more traditional personal path of getting married and having children with a romantic partner.

Zilis's initial plan for Musk's role in the lives of the first two children she had by him was not necessarily as an active father, and the two had agreed to keep his paternity "strictly confidential."

Today, Musk is an active participant in the lives of his now four children with Zilis, she said, explaining that they spend a few hours a week together as a family.

Zilis said the confidentiality agreement with Musk is why she did not disclose to OpenAI's chief executive, Sam Altman, that the twins she gave birth to in 2021 were fathered by Musk.

She told Altman that Musk was the father the following year, when she learned a Business Insider report on Musk's paternity of the children was imminent.

Nevertheless, Altman and OpenAI's president, Greg Brockman, wanted to continue with Zilis on the board of the AI company. Zilis said on Wednesday that the three remained friends until at least 2023.

When asked earlier this week about Zilis' involvement with OpenAI for years after Musk had left the company, Brockman said: "We trusted her to keep the Elon conflict under control."

Zilis left the board in March 2023 as Musk was launching xAI, an AI company developing a chatbot that directly competes with OpenAI's ChatGPT.

With years of history, including emails and text messages that have been made part of the case between Zilis, Altman, Brockman, and Musk, lawyers for OpenAI seized on several examples of discussions about changing the AI company's corporate structure.

Moving away from being a pure non-profit was seen as necessary as early as 2017 to enable OpenAI to grow and raise many billions of dollars from investors, according to written exchanges shown in court in which Musk was involved.

Brockman and another OpenAI co-founder, Ilya Sutskever, were pushing for the company to transition to a B Corp, a type of for-profit entity that holds itself to a specific mission.

Emails from Zilis showed that Musk wanted more control of OpenAI, through additional board seats and even suggested that the AI company become part of Tesla, possibly as a B Corp subsidiary of the electric car company.

Zilis said in a written exchange that such a move for OpenAI "solves the funding issue immediately."

Ultimately, Altman, Brockman, and Sutskever could not agree on terms with Musk, in large part because they were adamant that Musk "not have control" of OpenAI's work, according to an email from Zilis shown in court.