It's biological because its all about the brain. A person's brain makes them who they are.
Gender identity is a spectrum and no matter who you are, you have a place on it, whether you're a macho guy or a feminine guy or just kinda in between.
Every one is an individual and every one is unique.
I wish all kids were allowed to just be who they were and not be confined to strict gender roles.
God made each human being their own person.
I myself am not a "man" by society's expectations and standards, or a "woman". I just identity as other because nothing fits. Gender is not important to me. What matters is what kind of person you are.
People who insist that your physical body defines you from birth are just not seeing the bigger picture.
And by the way, a lot of Joe Six-packs are trans too:
I agree with your spirit of your argument, though I generally don't follow how gender identity (man, woman, other) is the same as a socially constructed gender role. Plenty of tomboys out there who still identify as women, after all. And I was not (and still am not) Mr. Macho (though I once tried and failed to be), yet I am nothing other than a man. Not sure I think *how* you are your gender reflects whether you *are* your gender. If that makes any sense. This is not a subject I'm well versed in.