I meant as much as we know ours now, not at age 4. I don't recall what or whether I thought about gender at all at that age. But I don't remember ever really thinking about my gender except in the context of conversations around gender topics like this one. Presumably for cisgender folks there's not normally any motivation to do so, any more than you'd spend time specifically thinking about other aspects of your person. But I can see how one would be much more likely to think about it if the gender they experience doesn't match their physical body and how others perceive them. And I've spoken to enough people with very similar experiences that I have no reason to doubt them.

And I guess that's what I don't understand about those who find transgender kids implausible. From what I can tell, the vast majority of transgender people will tell you they became aware of it in early childhood. Why would they lie? I can't come up with a speculation that doesn't sound like an absurd straw man.