The One Topic I Want To Censor (But Don't)

So there's one topic (or a set of related topics) that I don't want my daughters reading about and no, it's not what you think.  Both my girls know about the birds and the bees and have for a while and telling them was surprisingly easy.  But what I don't want them to read about - or know about - is the Holocaust.  And war.   And terrorism.  I find 9/11 particularly hard because it is not so far away - in either time or distance.  And the Holocaust feels close because, after all, we're Jewish.  I remember very clearly having nightmares about Nazis coming to get me as a child - in 1980s America. 

I was working at the school library the other day when my 8-year-old's third grade class came in.  And one of the books she selected was this biography of Anne Frank by Johanna Hurwitz.  I warned her that it might be scary, but she insisted she wanted it and so I checked it out to her.  Until now, the only thing she knew about the Holocaust was that the Nazis had been "mean" to the Jews.  She had read Number the Stars and The Night Crossing, both of which deal with escape from a Nazi-occupied country (kind of like in The Sound of Music), but neither of which address what happened to those people who could not or did not leave.

When is it appropriate to teach children about the Holocaust?  Or 9/11 or Newtown?  (Don't get me started on the terrifying potential of lockdowns - or, in my day, shelter drills.  I was convinced nuclear war with the USSR was imminent.)  Of course, the answer to that is "it depends on the child."  (Well, the real answer is never.  Are we ever ready to understand or confront evil?  I know I'm not.)   What are signs a child is ready?  I assume the fact that my daughter insisted on taking the book about, even after I told her it might be scary and was about a girl hiding from the Nazis, is sign enough.  But I wonder, will I be getting up tonight to comfort her after she has a nightmare?

Do you censor your child's reading in any way?  At what age did your child start reading about the Holocaust?  In school?  On her own?  Which books?