Some controlling tactics are more subtle than others but when combined with fear of disagreeing with or disappointing a parent, these can limit a young person's growth and ability to make his / her own decisions.
Excerpt from
http://www.wikihow.com/Cope-With-a-Controlling-Parent
Watch for attempts to isolate you or to trivialize the influence of other loved ones. Control is easier to establish and maintain if you have few people around besides your controlling parent(s). If your parent keeps you away from grandparents, aunts and uncles, or friends, it's a warning sign. Or, if your parent encourages relationships with others, but then says bad things about those people after they're gone, that's a clue, too.
Saying things like, "Your uncle is a nice guy, but for a guy so smart about trout fishing, he has no ambitions above where he is right now. His house is tiny, and he'll probably never be able to do any better than that," tells you that your parent does not respect your uncle at all -- in fact, this kind of remark is intended to influence your opinion and respect for your uncle. Perhaps your uncle is a nice and good person with low ambitions -- he may be content with little, and therefore shuns promotions -- he would rather have less money but more time to go fishing, which costs next to nothing. There's nothing wrong with this philosophy -- it is a simple life choice.
Your parent will have made a different one, perhaps his/her life choice is to be driven and rise higher and higher up the corporate ladder while your not-so-ambitious uncle prefers his simpler, less complicated life and doesn't mind that it also means he makes less money. The choice is value neutral -- it is simply a matter of preference in the big picture, but your parent doesn't respect anyone who doesn't constantly strive, clawing his/her way up -- again, a different philosophy and nothing wrong with it.
But -- your parent really doesn't want you taking your uncle's example, and what s/he is really saying is, "Listen to me, kid, because even though your uncle is nice, he's a loser, and you don't want to end up like him."
The parent then makes sure you realize that it's his or her own advice you should always take, and never anyone else's, utterly rejecting a different life philosophy, and in the process, attempting to persuade you to reject not only the philosophy, but the person.