Mentally-capable adults should be allowed to do whatever they want but children should not

Children are not fully developed until 25, and often, especially during adolescence, they don't feel like they are their birth sex. For most, this is just a phase that they grow out of. For those who don't grow out of it, they can transition once they are 18. The suicide rate actually goes up for transgender people (especially children) after they transition, as many regret this irreversible, life-changing operation.