Apparently George RR Martin, from A Clash of Kings.

Edit: Apologies, should have been in response to the sibling, rather than the parent.

Wow I’ve not heard this one before? Who said this? I love it.

This does not apply to Holocaust revisionism, before anyone even suggests it.

Sure it applies. In that case, there's just maybe some legitimate reason to fear it.

Imagine there’s an FBI raid on, or congressional investigation into, whatever American news outlet attacks your political beliefs, and I think you’ll find yourself believing not that the government must be scared of the truth, but that these guys didn’t deserve their tongues.

It’s easy to stand outside a regime’s borders and say it can’t change your reality, and comforting to believe that the truth always comes out in the end, but I think reality is more harsh: “History is written by the winners.”