In Americanah, Chimamanda Adichie’s new novel, she writes (p. 240):
Ojiugo wore orange lipstick and ripped jeans, spoke bluntly, and smoked in public, provoking vicious gossip and dislike from other girls, not because she did those things but because she dared to without having lived abroad, or having a foreign parent, those qualities that would have made them forgive her lack of conformity.
Here is another example, from a profile of Claire Danes:
She changed schools twice, “fleeing one mean girl only to find another incarnation of that same girl in the next school.” She was targeted for her looks, her nerdy curiosity, her refusal to conform.
My impression is that these examples illustrate a large male/female difference: Women will commonly criticize another woman for lack of conformity (unless somehow “earned”); men are much less likely to criticize another man this way. When women do it, it is called being catty. There is no equivalent term when men do it — presumably because no one invents a term for something that doesn’t happen.
I have never seen this mentioned in the literature on male/female differences (nor in Sheryl Sandberg’s Lean In). It isn’t easy to explain. Could it be learned? Well, in my experience girls are under more pressure to “act a certain way” than boys (Japan is an example), but I can’t explain that, either, nor can I see why that would translate to women putting pressure on other women to conform.
One reason this tendency is hard to explain is its effect on leadership. Putting pressure on other women to conform makes it harder for women to become leaders — leadership is the opposite of conformity. Making it harder for women to be leaders makes it easier for men to be leaders. It is hard to see how this particular effect (there are many others) benefits women.