Hacker

These days, they say we are literally a couple of years away from a computer that can emulate the human brain. A device that can represent the entirety of thinking, and break it down to 1's and 0's. Perceiving the way humans thinks as being in this fashion will help you understand. The structure of thought can be view as the coding that comprises "us", and just like coding it can be manipulated.
Through extensive research throughout the world, it's become known that certain vocal commands can actually overide the thought processes. The syllables are gibberish in any language, yet can render the target catatonic and open to suggestion. In the numerous tests, it was found that this state included an absolute abandonment of morals. Without question, fathers would willingly sacrifice sons, and life-long friends would turn against each other.
Over time, it was realised that this command code exists in the minds of all humans. At first the scientists were confused, wondering how the entirety of the Earth had become afflicted by this. Eventually it was realised that the condition is hereditary. This made the concept all the more confusing. For it to have spread in this manner, it would have needed to be introduced whilst humanity was still climbing out of the Cradle of Life, in Africa. This was long before any form of organized society.
For obvious reasons, information like this has been quashed at every oppurtunity. Can you imagine a world where every single person can make anyone within earshot a willing puppet? Life as we know it would fall apart overnight. Our lack of understanding prevent us from being able to remove this "control system", however through hypnosis we can establish when some has been used in this manner, but not how.
This is the point when those researching this started to get scared. They found large amounts of evidence that people were being used on a regular basis. We don't even know who by, of it was the same individuals who implanted the original coding into our brains when we were still scratching images of buffalo into cave walls.
It wan't until the indivudals were returned back to their original selves by repeating the syllables that outright fear set in. They would have no knowledge of what had happened, often expressing confusion and saying some variation of the same sentence.

"Hey, have you ever had that thing where you go into a room and you forget why you came in?"