Doesn't surprise me at all. Hey did your parents ever teach you things like these?
"You can do with your life what you want."
"Dress warmly or you'll get sick."
"Don't eat chocolate, eat an apple instead, it's bad for your teeth."
And if they did, would they get defensive and offended when another person just waltzed in saying 'Ma'am, why are you feeding your children to be ignorant, I've got statistics right here which transparently show that you have no control over what you grow up to be and very few children can realize their childhood dreams, why are you lying to your children like that and denying scientific fact? It's been established long ago that apples are worse for your teeth than chocolate, though chocolate makes you fatter."
Different things to lie about, same principle by which they lie, people have a hard time shaking things they've accepted to be true in childhood because it was all around them. Hell, I know some myths I could've put here that could give me an infraction for stating them, regardless if it's true or not, people are scared, not scared of the truth, not scared of lies, but scared of being exposed to the possibility that some things they learned as a child might not be true at all. And if some-one claims the inverse, people will get scared, and if that person has a good argument or not is pretty irrelevant and they fail to see the difference.
Edit, in the interest of making fun of interesting ignorance:
mentor edit: inappropriate link deleted