Social pressure is perhaps the most powerful tool of group mind control.  Group dynamics can subjugate an individual through shame, embarrassment, guilt, a desire to fit in, group euphoria, cohesion, exemplifying behavior, and fear of being rejected or shunned. 

When we belong to a group, we will often model the behavior we see in others.  We don't need to hear it preached from the pulpit or commanded from on high.  When we see someone else doing it, we often repeat the behavior in the hopes of being accepted.  It makes sense for the survival of the species -- in this way, successful behaviors are passed on to others.  This sort of observation-learning has even been seen in lower primates.

Perhaps it is no mistake that the Church often emphasizes setting and following a good example.  Youth are repeatedly told about the power of peer pressure, and the importance of choosing friends and role models who maintain "high standards".  

"...Your circle of friends will greatly influence your thinking and behavior, just as you will theirs. When you share common values with your friends, you can strengthen and encourage each other... Together you can maintain a high standard of gospel living." (For Strength of Youth pamphlet)

The Church is correct in this regard -- if it wants its members to follow strict cultural and behavioral patterns, it should try to isolate members from observing the behavior of outsiders.  

This pressure is not limited to imitation of behavior.  Spoken cues, folk lore, and how others are treated send messages of what is acceptable and what is not.  The Sunday School teacher may say, "Love one another!", but then later gleefully gossips to her friends about a gay member who was excommunicated, and announces that he got what was coming to him.  A Seminary teacher may give a lesson about how the spirit of the law is more important than the letter of the law, and then scold a student for wearing slightly immodest clothing.  The social cue is more likely to influence behavior, emotion, and self-image than actual talks and scripture references.

This sort of cultural teaching also gives the Church a plausible deniability for unhealthy behaviors or culpable doctrines passed along in this manner.  For example, apologists often claim members are not restricted from thinking for themselves.  Indeed, there are a lot of written works and spoken quotes declaring the merits of intelligence, reason, and freedom of thought, action, and speech.  But the social and behavioral records tell us otherwise.