In today’s world, there is only one primary group that is really common to the majority of people in our society. This is the family. It clearly has the greatest impact on us today. Groups of friends do have some degree of impact and religious groups have an impact on some people (and had more of an impact in the past).
America is still a very religious society compared to many others and the church can be seen (for some people) as a primary group. For such people, it can be a very strong influence on their values and expectations in such areas as sexuality, the family, and gender roles.
Friends can shape values for many people, particularly in adolescence. At that time, people are less certain of their own values and more likely to be influenced by those around them. They also crave approval. For these reasons, close friends can have a great deal of impact on them.
Family, however, is the main primary group that impacts practically everyone’s values and expectations. It is from the family that we learn what is acceptable and what is not. This happens both intentionally (when our parents do things like telling us what behaviors are expected) and unintentionally (as, for example, we observe how our parents interact with one another and with other people. These interactions account for much of our time as children and they are therefore the major factor that shapes our values and expectations.