Its the parents right (read: a just claim) to decide for  their child -- who is not of a majority age -- where the line is drawn between education and indoctrination; moral teaching and immoral teaching; civility and incivility. Because words form ideas and ideas have consequences, the words we use are important.  "Controversial" and "sensitive" only have meaning within a context.  I think the parent, to whom the child belongs and who has ultimate responsibility for the child's welfare, is the sole arbiter of this determination.