The author Steven Pinker has assembled the results of several studies on human behaviour and human nature into several books.
The upshot is that the most influence our parents have on us is at the moment of conception. 50% of our personality can be attributed to our genes.
More than 40% of the rest comes from the environment we grow up in outside the home -- the friends we have, the schools we attend, the neighboorhoods we build tree forts or play with Barbies in, the religious organizations and or boy/girl scout groups we belong to. And less than 10% comes from what our parents directly instruct us in under the roofs they provide for us.
Based on that, I don't think that the instruction that children receive is indoctrination so much as reinforcement of tendencies of attitude towards these issues that they already have. Children of bigoted parents often turn out themselves bigoted. But it's more due to genetics and growing up in a neighbourhood where everybody uses the N word or the F word.
I think these children, if presented 'diversity' curricula, may likely think it bull on first exposure because it SO contradicts what their environment has already established to be reality.
They can be shown another reality, and most will, to a greater or lesser degree, change their positions, though.
But we can't 'educate' with the naive notion that 'all we have to do is just' [teach our alternative reality]. If we do 'just' that, our message will skip off the armour of their worldview and spiral off into the void.
Donny Osmond and those who believe as he does can be persuaded to change their positions, but it has to be done with US understanding that position, getting inside it, and using persuasion to get them to WANT to modify their stances.
It doesn't necessarily have to in all cases be done 'nice', but it can't be done by dismissing their position as stupid, bigoted, uneducated or ignorant either.