I think I just read 3 of his "juvenile" novels (when in grade school) so they were tamer: Red Planet, Tunnel in the Sky, and Time for the Stars. The last is the one using the concept of telepathy. In Tunnel in the Sky one of the characters is a Zulu woman--when I read that I don't think I realized that that meant she was black.
It’s kind of a joke in parts of the SciFi readers’ community. After SIASL Heinlein kind of went off the deep end. ‘Time Enough for Love” is a real slog to get through with Lazarus Long very obviously being Heinlein’s alter ego. He became almost as unreadable as Asimov’s later output.