I’m one of your fans, and the educational point you make about the definition of ‘normal’ is really important to elevating the national discussion. However, a huge source of confusion is embedded in your otherwise really helpful diagrams: the terms ‘male’ and ‘female’ are used as the ends of both ‘gender’ and ‘physical sex’ distribution scales. This usage is widespread, and keeps the waters impossibly muddy. Even wikipedia maintains this problematic confusion within their definition of cisgender.
The binary male-female paradigm is built on the ubiquitous sexual dimorphism that drives evolutionary adaptation, and sociobiological theory argues convincingly that a lot of us make decisions based on efficiently finding desirable mates to help spread our genes. [Hence the generally averse disposition to trans people, as errors, distractions, or traps]
That said, evolutionary theory also supports the concept that essentially all genetic characteristics have value depending on circumstances, and thus the tails of every normal distribution exist to support future qualities in the peak. We trans people can freely tout our value, and of course, need to find circumstances under which to demonstrate it to willing observers!
You say, correctly, it is impossible even to define ‘physical sex’ precisely. This is even more true for ‘gender’, as it contains so many more attribute scales than do our sexual organs. Hence the idea that ‘cis/trans- gender’ is defined by more or less congruency between assigned physical sex and gender lacks so much precision that it is not useful to the goal of better articulated understanding and more productive and positive inclusion.
People operate at a visceral level, and certainly people understand what is meant by congruence between appearance or behavior and the cultural expectations promoted for one’s physical sex. This decision is still individual. Each person has a sense of what the binary cultural expectations are, and which ones they have agreed or subscribed to. Group dynamics come into play- when an individual asks for acceptance of behavior, simply by behaving in any particular way, other people [rugged individualists included] look at their group norms to decide whether to offer it or not.
If we were from another planet- we would scratch our heads at the imprecision of it all, and the loss of value to society from all the poorly founded and enthusiastically embraced efforts at exclusion. Perhaps we would offer a simple solution- Include everyone! There is huge value in each individual’s experience and desire to contribute- and the more we open ourselves to the definition of being human the more we all gain.