How far does the representation of a particular social group change overtime?

From An Education, which is about a family in the 1960's.  This family was portrayed in a different way to the family unit in Fish-tank. In An education the family was very close they spent time with each other and obeyed one another, an example of this is when Jenny's father made her study Latin despite her decision of not wanting to, she carried on with it to please her father. However in Fish-tank, which is about a family in present days, the teenager  Mia rebelled against her mother in every situation, they did not speak to one another and when they did it was in a spiteful manner. They had a very dysfunctional family, an example of Mia's rebellion is when her mother wanted her to go a behavior school and she never listened to her mother and completely disagreed with this idea. Styker's theory of a collective identity corresponds with the themes present in both films as Jenny is appealing to the wishes of her father, she reinforces her academic position in order to better herself from the standard that woman of the 60's were forced into at the time. Meanwhile, Mia has documented her mother's behavior and imitates it as a form of self defense. This social of a family changed dramatically overtime, as in the past it shows family in a positive aspect and in present days it shows family in a negative way.