"Gender identity cannot be externally measured, tested or verified. It is unquantifiable."
Nor can physical pain. Of course there are some people who don't experience physical pain, and they might claim that it's a delusion and it doesn't really exist, but all the rest of us who have experienced physical pain know that it does.
It can be objectively measured and imaged via brain scans, which have shown against all expectation that pain reception in the brain is surprisingly universal when it comes to physical pain.
"So, Shizuku, here is how I understand that definition explained."
And yet, millions upon millions of people and thousands upon thousands of doctors and scientists do not share your confusion.
An ad hominem is neither deserved by me nor worthy of you. If the points I make are wrong, then explain why. It's irrelevant how many people agree with your definition, the only thing that matters is whether my points are right or wrong. Engaging on this level of Graham's hierarchy of disagreement strongly suggests you have no counter arguments.
"It is innate and merely emerges like a butterfly from a chrysalis during childhood and adolescence and it is fomed in response to external stimulus."
We know there is a biological component, we assume that external factors might have some bearing on the way that biological factor is perceived by the individual or in the way it is expressed (non binary is a thing for example) but we also know that it's not something that can be forcibly changed.
As I have explained above, we do not know that there is a biological component for a universal gender identity. Having read all of the papers referenced in your links and many more besides, the only thing that researchers to date know is this:
There may be a biological component involved in developing gender dysphoria. This component has not yet been found nor is there agreement whether this is genetic, epigenetic, hormonal or neurological in nature.
I highly recommend reading the papers you link us to and paying particular attention to the caveats and limitations explained by the researchers who do not hide their uncertainty.
There is also a lot of evidence that trauma of various kinds play a strong role in the development of gender dysphoria. This is a developmental influence that is heavily researched. There is no suggestion that adverse childhood experiences merely help an innate (trans)gender identity emerge but that it develops in response to these negative developmental influences instead.
I mean do you think someone could force you to believe you have a male gender identity? And have they tried for years to force the gender identity of trans people to change with no success whatsoever? The answer to both is yes.
As I still don't know what you mean by gender identity, I cannot answer that. My analysis has laid out very clearly that to me that definition is meaningless because it is ideological and unscientific, internally contradictory and illogical at base.
However, having availed myself of all the various tests online, I not only measure as trans on the basis of my strong preference for masculine-coded stereotypes, I also met the diagnostic criteria for both gender identity disorder and gender dysphoria in my teens. In as much as I'm willing to entertain the notion, if I believed in gender identity, I would already be sold on having a male one.
As to your second point, it depends on who you are talking about. Transsexuals? Yes, therapy for those individuals has merely helped alleviate their distress and not resolve it completely. However, if you are talking about children diagnosed with gender dysphoria, the vast majority does indeed respond to therapy in successfully reconciling their mind with the body they inhabit (or in your language, these children who desist from their belief that they are the opposite sex do indeed change their gender identity. As do increasing numbers of detransitioners, who by now number in the tens of thousands.)
"It is a natural feeling like any other but differs from all other natural feelings humans experience in every way possible."
It's like many natural internal experiences. Pain, as I mentioned, is an example - you can't measure it and the only thing you have to go on is the person's claim that they are experiencing it. As you know, if you go to hospital in pain, they don't measure it - they can't - they just ask you to rate your experience of the pain you claim to have on scale of 1 to 10.
As I said above, pain can be objectively measured in brain imaging scans. It can also be elicited in predictable ways and measured in bodily responses. Much more importantly, gender identity is said to be a feeling like any other and yet, it does not change, we cannot be mistaken about it nor lie about it. Pain changes, we can be mistaken about it (there is a lot of research into that) and we can and do certainly lie about pain, too. So this analogy fails on all levels.
You can look for biological factors in both pain and gender identity, but ultimately, only the person in question knows whether or not they are experiencing it. And of course, you could refuse to acknowledge someone's pain or gender identity on the grounds that you don't believe they are experiencing what they say they are experiencing, but you know that the outcome of doing that in both cases can be extremely detrimental.
You say "ultimately only the person in question knows whether or not they are experiencing it". Do you concede then that gender identity is not universal? And that a person like me who says she does not experience this feeling of having a gender identity, does indeed know she does not have a gender identity?
Logically, gender identity cannot be both universal and a matter for each individual to decide whether they have one. So, which is it?
Am I mistaken about not having a gender identity, am I lying or do I really not have one?