Honestly, I think unschooling is great, but not unparenting. To me, if your child says I am not interested in anything math related, I want to play video games and you give her the Wii or Playstation or whatever, you are unparenting. If she says I am not interested in learning math and you say fine, would you like to cook with me? Or, stuff like that, you are ok. All children should still have responsibilities. They should still clean up after themselves and should still have community chores. They should not be allowed to engage in "junk activities" any more than they should have "junk food." If your child says "I don't want to eat this lunch" do you just say fine and hand your child a Hershey bar, a bag of chips, and a coke? Probably not. Same goes with activities. Even when I was unschooling, and right now, I am basically unschooling my 6 yr old, junk activities were and still are kept a limit. They are free to run and play, do their science experiments, watch educational TV, play educational computer games, read books, etc, but they are not free to just watch Simpsons or video games or anything else during this time. They also still have to do their family contributions. Today, both kids have had to pick up in the living room and kitchen and sweep and vacumm. Tonight, after 6, they will both get 2 hrs of screen time of anything of their chosing, which one picks computer games and the other movies.
I have no clue what you do in your home, but if your child is allowed to play video games (not saying she is) or watch junk on TV all day long, then she will never ever chose to do anything math related.
With my older children, I do require math, English, and spelling, and handwriting. That is it though really. They all place way way above grade level before high school. I teach them the tools they need to pursue knowledge in areas of interest.
I hope that helps!