Re: Very good skeptoid podcast recently debunking this stuff
"Asking somebody to explain it forces them to think about it. "
Unless they've already thought about it (or had someone think about it for them) and they already have an answer, such as "the brain--why do you think tinfoil hats exist?"
But if the question is repeated again and again with no malice or implication of stupidity, over time it might have an effect. Lots of us here will remember the long, slow decline of racism, sexism and homophobia... that is still going on, decades after it started. Ignorance is never dispelled overnight. Patience is required.