Is not all gender expression a fashion trend?
Boys don't play with dolls....says the parent.
Girls don't talk like that ...says grandma.
You can't wear that to school...says teacher.
All of those statements come from societal norms (fashion trends)
I think we get too wrapped up in the trend that is going on in OUR mind and then demand it in others under the guise of the fashion trend, manners, our expectations, the law, common sense, morality, or some religious scripture....we will grasp at whatever branch we can find to turn it into a switch and enforce our views on others.