Negative programming, or more precisely patterning, begins pretty much the moment you're out of the womb and engaging in your first interaction with your mother, possibly father and whoever else is in charge at the time – and quite probably even earlier while still in the womb. It's inevitable.
According to the Taoist way of explaining the mechanisms of existence, everything (and everyone) existing on the material plane is subject to the underlying subatomic dynamic of 'yin and yang', negative and positive – you obviously can't have one without the other – a degree of negative patterning will be transmitted to you and imprint itself on your psycho-neural circuit boards from the start. And because you're wide open without preferences, or even a way of categorizing or recognizing yet what might work to your benefit and what might not, you're utterly defenseless and susceptible.
And because as a newborn you're hypersensitive it takes only the most minuscule degree of negative stimulus to trigger trauma, however minimally.
It could be an askance glance, a roughness in the way you're being handled, an impatience to put you down, irritation at your crying, thinly veiled or blatant disgust at your eliminatory activities, or an unkind, loud, strident, abrasive, of even fake-nice (hence perceived as sinister) vocal tone. Your mother could even have been suffering from post-natal shock turning to depression, or your father may have been under such financial duress and hence so afraid and on edge that he snapped at you.
Or your parents could have simply been inept at being their authentic selves and articulating genuine emotion in a resonant way. The result is alienation. With alienation comes a sense of isolation, and of course of being abandoned – obviously one of the scariest, most unsettling sensations for a tiny helpless baby.