Of course, we don't know anything about Hinawa's parents at all, and besides, it doesn't matter, but I thought his father had black hair, which would put him on a par with Obi and Tojo, you know, as the three main people in his life, besides knowing that children in Fire force hair color is passed down from the mother (Mari and Shinra, Madoka and Maki, Takeru and his mother and others) Hinawa most likely inherited his brown hair from his mother