My parents took me to see this movie when I was probably 12 or so. My parents exposed me to quite a bit of questionable culture (I tend to now have odd, eclectic taste, but I wasn't terribly scarred).
This Ken Russell movie has never been made available on DVD, which is great crime. It's over-the-top, and it's bad history, but it is a remarkable movie.
That's a good thing because you develop an open-minded appreciation for stuff. It's often the questionable stuff in art, music and literature that we remember from our youth.
The only material that I really feel like protecting my children from is the graphic sex and super-realistic violence. Otherwise, everything else is fair game.
They may not forgive me for dragging them to Peter Sellar's operas though.