Rearing children at all is brainwashing. I'm sure somebody has already said that. Not teaching them your religion is brainwashing. Making them wash dishes is brainwashing. Any mistake you make, including letting them watch too much TV like my parents did, is brainwashing. Its all brainwashing, legal, normal and necessary unfortunately. I mean, even if you let them rear themselves in the woods like wolves, its still brainwashing.
Doors of perception said:
sharing your ideas with them as they enter adolescence and allowing them to reflect and make the decision for themselves
I'm very late to the thread, but sharing ideas with adolescents and children is the same thing as telling them. You can try to make them believe it, but its about as effective as just sharing it. Teaching them anything is the challenge.
Now what I think is damaging to children is when a parent never ever lies to them about anything or conversely when they cannot trust their parents. Those are two extremes. If you never, ever lie then that is very strong brainwashing. Kids need to learn not to lie, but they should still know how to do it. It handicaps them if they can't comprehend lying. They also need to learn to value trust, and lies help with that, too.