In the book Ishmael by Daniel Quinn What does Ishmael mean by Mother Culture?

It is not a real entity, just as Mother Nature isn't. I believe that's why he chose the name. Mother culture refers to the voice in your head that tells you how to think and act 'normal' in your society. It is TV ads and movies and fairy tales and laws and school lessions that all are based on the same underlying values. It is reinforced by everybody around you buying into the program without ever really knowing there is a program.

Mother culture is a subtle influence and much of it is not explicitly said. It is a bias on how you observe the world, the tint in your ski goggles when the world looks slightly yellow.