I definitely think that kids can and should learn about social sciences if they're interested. DK has a wonderful series for kids (maybe aimed at ages 8-12) that introduces social science topics. One of the books is called "Show me the money: How to make sense of economics." My DD7 loved reading this book because it introduces complex and interesting topics that are not covered in school. It's got beautiful charts and graphics that help make it accessible and interesting. She's definitely able to relate the ideas to what she's experienced in her life. She also enjoyed "What do you believe?" (in that series) which has a very contextualized overview of different religions and discusses the idea of belief and non-belief in general. There's also a book on psychology (What goes on in my head?) and Government (Who's in charge?). These books introduce ideas that get her wheels spinning. I really wish there were more of these kinds of materials available, but there are some amazing YouTube channels that my daughter loves that present complex concepts in an accessible way: SciShow, Vsauce, CrashCourse, Ted-Ed, CGP Grey, etc. At this age (7) I don't think she'd be interested in the books recommended by JonahSinick, but I will make note of them for later.
