OK, thank you. That helps clarify what you're asking, and I think it's a genuinely interesting question.
First, again, what I'm referring to as gender identity is our recognition of ourselves in relation to sex categories such as male and female, boy and girl. For most people, that recognition corresponds to their physical sex, so it's completely unremarkable. It doesn't necessarily feel like anything. It's simply something they know about themselves.
But that's true of a great deal of human cognition.
Consider again the example of recognising your own arm. What does recognising that your arm belongs to your body actually feel like? I couldn't tell you. You might say you know it's yours because you can see it or feel it, but as we've discussed, neurological conditions such as somatoparaphrenia demonstrate that bodily ownership isn't simply derived from those sensations. Some patients can see and feel their arm but don't recognise it as their own. Conversely, someone can lose movement or sensation in a limb without losing their recognition of it as part of their body.
The point is that much of our cognition happens automatically, through processes operating outside conscious awareness. We experience the result of those processes without necessarily having direct conscious access to how the brain produces it.
So if I asked you what recognising yourself as a woman feels like, you might reasonably answer that it doesn't feel like anything. You simply know you're a woman. You wouldn't necessarily be able to describe some distinctive internal sensation of femaleness.
And this is what I'm suggesting is also happening when a young gender-incongruent child identifies as a girl or boy.
When researchers and interviewers ask young children how they know, they give simple answers: "I just am", "I felt it inside", "my body feels it", "on the outside I'm a girl, but inside my head I know I'm a boy".
People objected and got very indignant when I previously shared examples like these because they felt the answers were insufficient. But insufficient for what? They weren't intended to establish whether a child should receive medical treatment. They were examples of children attempting to describe their own identification.
Of course, if a child said, "I know I'm a girl because girls wear dresses and I like dresses", that would tell us something quite different. It would suggest that their identification was being explained through a gender stereotype, and that would be important to explore.
But when a child says, "I just know I'm a girl", we shouldn't automatically assume there's some unarticulated belief about dresses, toys or other characteristics behind that recognition. There may be underlying cognitive processes that the child simply cannot explain.
Now, your second question is how the child comes to recognise that experience specifically as belonging to the category "girl".
And that brings us back to the original hypothetical about a child raised without human contact.
Would such a child know they were gender-incongruent? We don't know. They might experience some vague sense of disassociation from self ("something feels wrong, I just don't feel like me") or bodily incongruence or discomfort without understanding it. They might experience nothing identifiable at all. Without the concepts of male and female, boy and girl, they couldn't recognise or describe their experience in those terms.
But children ordinarily develop within a social world in which those categories are constantly used. They acquire the language and concepts through which they can understand and interpret their experiences.
In that social world, being called a boy might feel wrong or confusing, while being recognised as a girl feels right, or brings a sense of relief. Through repeated experiences of that kind, the child may come to recognise and describe their identification using the socially acquired concept "girl".
That doesn't require the child to know what being female feels like for other people. Nor does it require them to identify some characteristic that all girls share and consciously conclude that they possess it.
It requires the development of gender concepts and the possibility that underlying neurocognitive processes contribute to how the child experiences their own relationship to those categories.
Now, it's true that we don't currently know precisely what those underlying processes are, or how they work. That's a fundamental limitation in our understanding of the brain/ cognition, and our ability to observe how it works. It's an empirical question, not something I'm claiming to have settled.
But I think it's a mistake to assume that, unless a child can articulate some specific content or definition that explains their identification, there can be no underlying cognitive basis for it.
We routinely recognise things about ourselves through processes we cannot consciously describe.