Nobody explains things morel clearly than Ben Joravsky in the Chicago Reader:
Central-office officials have not clarified who brought Persepolis to Byrd-Bennett’s attention. But it’s widely assumed that it all began with a complaint from a parent about the book’s interrogation scene, which features a drawing of a fully exposed agent for the secret police urinating on a prisoner he’s torturing.
Hence, the great parent-penis theory: Byrd-Bennett got a complaint, saw the picture, and freaked out.
If so, let’s take a moment to appreciate the irony. For the last few weeks, thousands of parents have begged and pleaded that Mayor Emanuel not close their schools. And Byrd-Bennett’s basic response has been: I know you’re “emotional,” but we know what’s good for your children.
But get one parent complaining about one penis, and the world moves.