Back with an apology – and Arnold Schwarzenegger still has half an eye on the White House

Film star admits in new book that he fathered illegitimate child while Governor of California

Calling it "the stupidest thing I've done," but seeming only vaguely apologetic, Arnold Schwarzenegger has told how he fathered an illegitimate child with his housekeeper and kept the infidelity secret from his wife and children, and the voters who elected him Governor of California.

In a round of interviews to mark yesterday's release of his autobiography, the Hollywood actor said he never actually spoke to his employee, Mildred Baena, about the provenance of their son Joseph, born in 1996. Instead, Mr Schwarzenegger realised that he was the father seven years later, when the child began to resemble him.

"It just appeared to me there was something off, that he started looking like me," he told the US television network CBS. "So that's when I kind of got it, it was never discussed." Schwarzenegger, who was running for election at the time, started making regular extra payments to Ms Baena, who remained a salaried employee. Although the cash transfers continued throughout his Governorship, he denied that they constituted hush-money. "It just felt like I should start taking on responsibility for him and her. And so I started taking care of Joseph financially," he said. Schwarzenegger's wife, Maria Shriver, learned of the affair the day after he left office in 2011, during a meeting with their marriage guidance counsellor. The couple, who have four children, promptly separated and are still negotiating a divorce.

"Maria said 'Hey, I think that Joseph is your kid. Am I off here or not?'" Mr Schwarzenegger recalled. "I said: 'No, you're absolutely correct and I'm sorry. I think it was the stupidest thing I've done in the whole relationship. It was terrible. I inflicted tremendous pain on Maria and unbelievable pain on the kids."

The tale is the major talking point to so far emerge from the ghost-written memoir Total Recall. Still unanswered, however, is the question of why a man worth around $400m should have decided to undergo the tawdry process of publishing a warts-and-all autobiography.

One potential explanation is that Ms Shriver, a member of the Kennedy dynasty, is rumoured to be entertaining offers for her own memoirs. Another is that Schwarzenegger still harbours political ambitions. Though born overseas, meaning he'd have to first secure an amendment to the US Constitution, the actor has long fancied himself as a potential Republican presidential nominee.

"This is all about positioning and damage control," Ian Halperin, author of his biography, The Governator, told The Independent, "Crazy though it sounds, Arnold still wants to run for the White House."