Seven people A, B, C, D, E, F, and G went to watch a movie. A is the only son of B. B  is the mother of C. D is the grandmother of A. E is the sister-in-law of B. F is the daughter of E. G is the father of F. G said, "I will sit right next to my only niece". If G doesn't have any sibling, whom is he talking about?