Errol Musk, the father of Tesla CEO and billionaire Elon Musk, said in a radio interview on Monday that his billionaire son was not his favorite, appearing to minimize whatever accomplishments his son had and extolling instead Elon’s brother Kimbal.

In an interview with the Australian radio program The Kyle and Jackie O Show, the Musk patriarch appeared to minimize his son Elon’s accomplishments when asked by the radio hosts if he was proud of the SpaceX CEO, according to the Guardian.

“No. You know, we are a family that have been doing a lot of things for a long time, it’s not as if we suddenly started doing something,” he said. 

He then explained further that Elon shared to Errol that he felt like he was running “behind schedule” on some of his accomplishments and goals, an assessment that Errol agreed with and shared with the hosts, the New York Post reported. 

“He is frustrated with progress and it’s understandable,” he said. “I know it sounds crazy, but we tend to think like that as a family. He’s 50 now and I still think of him as a little boy. But he’s 50, I mean that’s an old man.”

During the interview, Errol also compared his eldest son Elon to his younger son Kimbal, a restaurateur who is worth $700 million and who owns The Kitchen Restaurant Group in the United States. Errol called Kimbal his “pride and joy,” while taking a swipe at Elon’s appearance and health.

“Elon is very strongly built but he’s been eating badly,” he said. 

Errol has three children with his first wife, Maye Musk, and five other children with other partners. Controversially, he has at least three kids with his stepdaughter, Jana Bezuidenhout, with whom he has a 42-year age gap. Asked about the ethics of that relationship, Errol claimed that it was “completely normal” for him to be with her. 

Towards the end of the interview, Errol also stated that the Musk family was frugal, claiming that his son Elon did not give him handouts for free. He also claimed that in his slate of luxury cars–which include a Bentley, a Rolls-Royce, and a Mercedes-Benz–Errol did not own a Tesla personally.

GettyImages-1241046919 Errol Musk, the father of Tesla CEO and billionaire Elon Musk, claimed during an Australian radio show that Elon is not his favorite child, favoring Elon's younger brother Kimbal instead. GIANLUIGI GUERCIA/Getty Images.