Elon Musk's biographer Walter Isaacson revealed in a new book published last week that Musk had long been concerned that his father, Errol Musk, was paying too much attention to his underage stepdaughter, Jana Bezuidenhout. More than a decade later, Musk and his adult stepdaughter had two children.

"Errol, then 56, was unnerving Elon by paying too much attention to his stepdaughter, Jana, who was 15 at the time," Isaacson wrote. "Elon was furious with his father for what he believed to be inappropriate behavior, and he developed a deep empathy and a sense of intimacy with Errol's stepchildren. He knew what they had to endure."

Isaacson wrote in his biography that in 2002, Musk persuaded his father to move from South Africa to Los Angeles with his then-wife and stepchildren.

Musk bought them a Land Rover and a house in Malibu, Isaacson wrote. But after about a year, Musk began to worry about his father's attention on his stepdaughter. So the Tesla CEO bought his father a yacht on the condition that Errol Musk would live alone on the boat and only see his family on weekends.

Elon Musk told Isaacson: "I tried threats, rewards and arguments to make things better for my dad. But it wasn't possible and it got worse."

Musk's father, Errol, responded, calling the claims "nonsense."

"I took care of all five of my kids the same way," Errol said, adding that in the early 2000s, he tried to pay special attention to his stepchildren because they told him he seemed to prefer his biological children.

Errol described what he said was an incident in November 2002: "There was nothing uncomfortable. One afternoon I went to Jana's room to fix the light in the dressing room, which Jana asked me to do, but when Jana found me in her room she complained. I understood her concern and agreed to ask her first next time. That was it."

In 2003, Errol Musk left the United States without telling Musk and returned to South Africa with his family, who had to take extra steps to enter the country because Musk "took their passports."

Errol Musk said his 2004 divorce from Heide Bezuidenhout made Jana no longer his stepdaughter.

Errol Musk said Jana moved in with her in 2014 after Jana was "kicked out" by a man she was living with and had nowhere to go.

In 2017, Errol Musk gave birth to his first child with Jana, who was in her 30s.

Isaacson writes in the book that Elon Musk and his brother Kimbal Musk were "horrified and angry" at the news of Jana's pregnancy.

Kimbal Musk told Isaacson: "I was actually slowly making peace with my dad, but then he and Jana had a kid and I said, 'You're done, you're out. I never want to talk to you again.' I haven't spoken to him since." "

Isaacson said in the biography that Elon Musk began giving his father a monthly stipend of $2,000 to $5,000 in 2010, but suspended the funding when he learned his father had a child with his ex-stepdaughter.

According to Isaacson, Errol Musk later gave birth to another child with Jana in 2022, and Elon Musk learned the news on Father's Day that year.

Elon Musk's complicated relationship with his father is a common topic in this biography. His ex-girlfriend Grimes told Isaacson that Errol Musk had distorted the Tesla CEO's view of love to a certain extent.

Today, Elon Musk no longer speaks to his father, according to Isaacson.