My son Liam is ten now. He requests sushi out at least once or twice a month, and also occasionally rolls his own (he's got the mat, etc., and we pick up ingredients when there's something he wants to put together). He also makes (and eats, and apparently enjoys) some kind of Japanese "sticky rice ball with plum" concoction.
He didn't get it from Mom and Dad. I mean, we've both eaten sushi and are fine with it when he brings it up (I'm not very experimental -- I generally stick with California roll or spicy tuna), but I don't think we ever prompted him or anything. I guess I probably ate sushi one time between his birth and the time he started asking for it (at a buffet in Austin, Texas when he was three years old).
I'm guessing he picked the idea up from anime/manga.
I may have to take him to see this: