Social Control

Start with a cage containing five monkeys. Inside the cage, hang a banana on a string and place a set of stairs under it. Before long, a monkey will go to the stairs and start to climb toward the banana. As soon as he touches the stairs, spray all of the other monkeys with cold water.

After a while, another monkey makes an attempt with the same result, all the monkeys are sprayed with cold water. Pretty soon, when another monkey tries to climb the stairs, the other monkeys will try to prevent it.

Now, put away the cold water. Remove one monkey from the cage and replace it with a new one. The new monkey sees the banana and wants to climb the stairs. To his surprise and horror, all the other monkeys attack him. After another attempt and attack, he knows that if he tries to climb the stairs, he will be assaulted.

Next, remove another one of the original monkeys and replace it with a new one. The new comer goes to the stairs and is attacked. The previous newcomer takes part in the punishment with enthusiasm. Likewise, replace a third original with a new one, then a fourth then a fifth.

Every time the newest monkey takes to the stairs, he is attacked. Most of the monkeys that are beating him have no idea why they are not permitted to climb the stairs or why they are participating in the beating of the newest  monkey.

After replacing all the original monkeys, none of the remaining monkeys have ever been sprayed with cold water. Nevertheless, no monkey ever again approaches the stairs to try for the banana. Why not? Because as far as they know:

"THAT'S THE WAY IT'S ALWAYS BEEN DONE AROUND HERE"

And that, my friends, is how any society (gang, company or a nation) comes to being...

• https://en.wikipedia.org/wiki/Social_control