Is Sister Yuan in my hometown really a brother and sister?

No. According to official information of Tik Tok, Jie Yuan was originally named Li Yuan, a native of Heze, Shandong. She became an online celebrity because she released some short videos about rural life and funny stories, which gradually became known to the public. The so-called siblings of the opposite sex are actually partners, and the role and story are all a kind of square-fiber waiter-style to enhance popularity.