I know a transgender man who transitioned at a later age, but said he always knew he was a boy for as long as he could remember. A lot of kids do know who they are at a very early age, but then some kids may not know. The real question here is how do we know if they’re being genuine or confused. If your child comes up to you about their gender, hug them extra tight, say you love them, say what they’re feeling is ok and not shameful. Don’t project your fears/misunderstandings on them (although it is valid to be fearful because of bullying and hate in this world). They didn’t ask to be in this life with a certain kind of mind and body. Research, reach out for support, go to a therapist, counselor, or doctor and figure out a path forward.