Elon Musk has 11 known children with three different partners. His first child passed away at 10 weeks old due to sudden infant death syndrome. The rest of his children include twins, triplets, and several others with musician Grimes and Neuralink executive Shivon Zilis.
Elon Musk has mentioned the "collapsing birth rate" concern multiple times. In 2022, he tweeted about it and also discussed it during an interview with Tucker Carlson and at the Milken Institute conference. He has emphasized that a declining birth rate is the biggest danger civilization faces.
Musk had a sexual relationship with a former SpaceX intern, who he later hired onto his executive team. This information was revealed in a Wall Street Journal report which also mentioned a second employee who had a sexual relationship with Musk.