What is less harsh than "brainwashing"?
Solution 1:
The word "institutionalized" is sometimes used euphemistically to refer to a successful organisational attempt to control people's thinking and belief systems. e.g. They have been institutionalized. Sample articles that use it thus:
https://www.linkedin.com/pulse/corporate-employees-who-have-been-institutionalized-you-mele
https://www.goodreads.com/quotes/791525-humanity-has-been-institutionalized-and-we-are-all-the-products
Solution 2:
There is 'Indoctrination'
Indoctrination - noun
1 - the act of indoctrinating, or teaching or inculcating a doctrine, principle, or ideology, especially one with a specific point of view: religious indoctrination.
www.dictionary.com
Solution 3:
Consider,
molding/(Chiefly BrEng) moulding.
mold: to shape or influence; give direction to; mold public opinion Wordnet by Farlex
conditioning
condition: train or accustom (someone or something) to behave in a certain way or to accept certain circumstances: Oxford Dictionaries
training
As in, We've been trained (through advertising, media exposure, etc.) to fear/hate certain things and to be attracted to others. Google
train
a. to coach in or accustom to a mode of behavior or performance.
b. to cause (a plant or one's hair) to take a desired course or shape, as by manipulating. AHD
Solution 4:
Consider inculcation:
inculcate: to teach (others) by frequent instruction or repetition; indoctrinate
(AHD)
Another alternative not yet mentioned is ingraining:
teaching or impressing upon the mind by frequent instruction or repetition
(WordNet)