The father of Elon Musk said during an interview that he isn’t proud of his billionaire son, saying that Elon is unhappy with his own career progress, writes The Guardian.

During the interview with the Australia radio The Kyle and Jackie O Show, 76-year-old Errol Musk was asked if he was proud of Elon’s accomplishments. Errol replied: “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”.

Errol conceded that Elon, the founder of Tesla and the chief of SpaceX, has accomplished quite a bit in comparison with his siblings.

“They’ve seen a lot of things, and we’ve done a lot of things together”, said Errol of his family, referring to his clan’s travels to China, the Amazon rainforest, and other places. “But Elon has in fact sort of really surpassed the mark.”

Errol continued discussing his son, saying that the younger Musk feels “behind schedule” in terms of where he wants his various companies to be, and is “not as happy as he’d like to be”: “He is frustrated with progress and it’s understandable. 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”.