Does dark include truth as well?

That was Mr. P.K. Mukherjee's question in response to Joydhk's question on what should be the content of children's literature.
As Joydhak does not have enough vocabulary to give a conclusive definition of "Dark" in this context, we shall try to elucidate with an example:

Let us consider the recently published news of a sex maniac monster and his daughter in the dungeon for more than two decades. Its a truth. Its reality. Its dark. That is Joydhak's perception of "dark" so far as children's literature is concerned. That is what Joydhak denies to dish out to children.