Yes, that is a very lawyerly answer that we give so often and under so many circumstances; however, we cannot, as lawyers, tell someone whether to identify as a male or female.
People recently highlighted a family with a six year old transgender daughter. The parents made the choice to allow their child, who was assigned male at birth, to fully transition to a female at the age of four. Although it was surprising to read about a child who had transitioned so young, it is not shocking that a child of that age made it clear to their parents who they were and how they identify.
Transgender laws are developing. Many of the current laws specific to the transgender community involve civil rights, but others include change of name and hate crimes. We expect that many other areas of law will continue to evolve and change as well.
Some resources that might be useful: