My parents also tried this quite a lot, and still do when they have the opportunity. I found that a statement of "you like/want X" caused me to have an opinion about X, I'm reasonably confident this caused me to have the opposite inclination at least as often as the intended one. I don't think there's an age limit on this tactic having some effect, though not necessarily the intended one (though there is at least some projection from my own experience going on there, so discount accordingly).