The Nail That Sticks Up Gets Hammered With Status-Quo

The "Status Quo" of any culture is maintained by controllers, so those who don't fit in are targeted. This can be seen in most  human cultures, smaller communities, groups, and families.
It is Controllers who lead the "hammering down" of the "nail that sticks out", it's not something that "just happens".

First, children who are seen behaving outside of the very small window of compliance are usually targeted with facial expressions and intonations from adults around them. Approval and disapproval tones, expressions and words are used to teach and guide infants in a genuine way, about right and wrong, safe or unsafe, and polite or impolite. But the same tones, expressions, and words are used to "correct" and "guide" babies and young children to comply with stereotypes, and conditioned submission to social control signals. In other words, a little girl may be subtly admonished for trying to walk all the way across the room and grab a toy from the table, but a little boy may be smiled at and given obvious approval for the exact same action. A little boy who puts on a hat at the store may be subtly scolded or given disapproval expressions, but a little girl who does the same thing may be smiled at and encouraged.

Then, they are conditioned using control tactics such as taking toy trucks and tools away from little girls and giving them to little boys, trying to provoke little boys to behave in a more aggressive or hyper way, or making little girls wear certain clothing that's obviously uncomfortable or they don't like, that boys are not made to wear.

These early attempts at conditioning are not done across the board, not all parents do these things. So as children get older, those who were not conditioned in this way at home, OR if they were, it didn't "take", are then targeted by those in the larger group. They are often singled out with small acts of shaming, such as making fun of a little boy who plays with dolls, or who is good at creative expression.

Then they'll directly admonish a child for displaying feelings or motivations that don't align with the "culture", such as showing care and empathy for animals, or not acting mean or dominant toward smaller children, or children of the other sex or other races.

As children get older, the acts of bullying, shame, and rejection grow more and more severe toward those who don't "fit in" with stereotypes, and who don't comply with the local Controllers' illusions of social hierarchy. Those who stand up for others against bullying, unfairness, and injustice are always targeted, especially if they don't have a larger group backing them up. Those who do anything outside of their "gender role" box are usually targeted (girls who aren't afraid of snakes, boys who don't care about sports, for example).
~~~Those who DO NOT respond with SUBMISSIVE social signaling to those who seek dominance and control are almost always targeted. They don't have to "REBEL" to get targeted, they just have to NOT SEEM TO NOTICE that a Controller is apparently "Very important", "Large and In Charge".
(If a person is not recognizing a Controller's "authority", then the person is a threat, because they aren't intimidated.)

Children who don't comply with the Controllers in a group (both adult and child Controllers) will be treated with increasingly aggressive and manipulative forms of bullying and sabotage as they grow. The older and larger a child grows, the less empathy and sympathy from others is seen, which means the less protected from bullying and manipulation the child will be in the culture or group.

This occurs in every human culture, however the less generally mature a group is, the more it occurs, and with more severity. Hence cultures that are rife with barbaric practices surviving intact, generation after generation, with little or no change, and cultures who pretend to be "equal" but desperately avoid talking about the reality of their status quo and their real-life behaviors are quite the opposite of "equal". 

"The nail that sticks out is hammered down."
(Japanese proverb).
This "hammering" starts in a child's first year of life, it doesn't start in adolescence. It starts with light tapping, and grows more and more violent over time. 

The WINDOW of compliance to the "Status Quo" in a given human culture or sub-group is usually VERY SMALL, as can be seen by those who live outside of a culture or group; how they dress, talk, walk, carry themselves, the way they treat one another, and what they seem to believe. However, most who live INSIDE of a culture or group seem unaware of their own conformity to one another, or to their behavior toward others in the group.

When a person can't be made to comply with the cultural Status quo, with the standing 'hierarchy', and the behaviors and the stereotypes, they are typically REJECTED from the group. People will do all kinds of things to cut the person off from social groups, social interactions, social connections, and from business connections as well. Controllers LEAD this rejection behavior, and others follow along because they're more concerned about being accepted by the group than the rejected individual's well-being.

It's NOT about the person's real character, or their "right or wrong" actions. It's about the fact that they aren't complying with those in the group who want to be in charge of the group. Gender roles and racial stereotypes are all about keeping control over others, and rejecting people for non-compliance to these roles and stereotypes, regardless of their character as a human being and how they treat others, is PROOF of that.

The fact is, in most cultures, the adult that gets "hammered down" has probably been getting "hammered" since they were very young. Many don't realize what's going on, because Controllers consistently blame the person who doesn't fit in for the ill behavior of others toward them. Many buy into the bullying and shaming tactics, believing that they're just "too weird" or "too different" for others to like them, and end up suffering from lowered self-esteem, even depression.
Character is about behavior and integrity, how we treat others and how we conduct ourselves in regard to real values, not about conformity to stereotypes and roles, or complying with someone's desire for grandeur and control. Those who treat others poorly because they don't "fit in" and conform to a stereotype expectation, or because they don't go along with all of the opinions and preferences of the group, are displaying poor character, not high moral character.