It's not about pretending and it's not about a trend; it's about exercising caution. It is common that I hear nowadays that children "know who they are." To a great extent, no they do not. They are evolving, they are developing, and it would be unwise as well as potentially neglectful for a parent to take them for their word that they identify as "trans" or however one wants to word it, and grant them access to puberty blockers and other necessities for transition. Being trans might be legitimate for some, but being trans might not be for others because of self-misconception (something that is prominent throughout childhood and adolescence). Many, I'm sure, don't want to transition because it's cool, but because they believe that going through with such a thing will alter any present dissatisfactions or conundrums with their very own selves.