Hi there EveningRose, and what a wonderful topic you have brought up
In a _healthy_ family, like others have pointed out, "roles" are flexible. They are based on an individuals personality, the needs of the family at the time, and how the adults hand out responsibilities in a gradual and age-appropriate manner.
In a dysfunctional family the adults are only adult in age. They are still operating at some under-developed emotional stage. What "roles" get forced on the children depends on what the needs are of the particular dsyfunctional adult. There is a popular mythconception that roles are based on birth order, but that's not the way it happens in real life.
If the dysfunctional adult is physically irresponsible then the first child gets stuck with being the "over-responsible" or "hero". If the adult is emotionally isolated then the first child gets stuck with being the "golden" or "baby" of the system. As more children are added to the system they get to fill in whatever other roles the adult is unable to do on their own.
And as far as "people treat you as you teach them", that applies only to _people_. Dysfunctional adults are not "people", they are a weird hybrid of a physically old body with an emotionally stunted brain. They are closer to dogs than humans. With dysfunctional people you can not _teach_ them, you have to _train_ them, which is an entirely different concept.
Healthy people are aware of their surrounding and the impact they have on others. So you can teach them simply by communicating your own needs and responding to theirs. Dysfunctional people live in a fantasy of their own imagination and have no awareness of the existence of others. So you have to figure out their individual fantasy, their bizarre needs and you have to offer them some kind of "reward" for doing the right behavior.... over and over and over until they "get" it.
Just like a dog
Mike