There can be, there has been many many instances of brainwashing and conditioning whereby people have had their actions and even thought patters controlled by various outside stimulus, including verbally. It is just quite difficult to do with most humans because we live in a society where that is not done often. But if you get someone from birth, and are able to influence them freely you can do practically everything that you see done with synths. They just happen to be made with a built in command phrase, while we currently lack the ability to do the same with humans.
Edit; Furthermore, the more we learn about how the human brain works, the more control we have over it. It is not insane to think some day we would have the ability to control someone to a much larger degree and much easier than we do now. A little chip inserted into the brain could have easy and complete access over all the little electrical impulses that control all of our thoughts and actions. We lack that ability now, but just because the institute can do it with synths, doesn't make them any different than humans.