I want to make a few things clear before I go any further: body / gender dysmorphia is not something that magically begins at the age of 18, and the idea that treatment for it should be held off until that age is as ridiculous as implying depression or anxiety not be treated until then. There’s also a myriad of reasons as to why someone under 18 would want to seek this treatment without their parents’ knowledge.

And in fact if you wait until 18 to provide any treatment, they’ll probably have greater dysphoria for the rest of their life from a puberty that is only partially reversible since you made them wait years without HRT or blockers, and usually requires surgery orders of magnitude more expensive, time consuming, and painful than early blockers would’ve been