Teen years are developmentally about identity and finding yours whilst also being included as of your peers' group identities.
Some think it was anthropologically useful for tribal bonding and the next generation of adults. There's a psychosocial development theory developed by Erik Erickson that 12-18 is a phase for identity development, lots of 'testing out' of roles and responsibilities and relationships. www.simplypsychology.org/erik-erikson.html
"Identifying as trans" It's a very obvious part of this process, especially, as we know, within sexist cultures whereby gender stereotyping is very prevalent.
Despite attempts to challenge stereotypes, Visual media on the internet and in the gaming world is still overwhelmingly very stereotyped.
Obviously teens will absorb the visual culture around them, as most of us did somehow (goth, emo, punk, horsy kid) mash it into experimental identity stuff and then move through it.