Autism. ADHD, in hyperactive, inattentive, and mixed. Synesthesia.
Imagine for a moment that there is a world with two main tribes of sentient beings. They're both the same kind of creature underneath in that they can interact and even breed. There's one main difference between them. The Aerials can fly. The Terrestrials cannot.
Now that's actually not a huge difference on the face of it, but it does result in the development of two different societies. The Aerials don't bother much with roads or sea travel. Why would they? They can fly. The Terrestrials have roads, bridges, ships. If you asked who was more technologically advanced, you'd say the Terrestrials. But the reason the Aerials haven't built as much infrastructure is because their living conditions don't require it. They aren't stupider than the Terrestrials. On the other hand, the Aerials have conventions that Terrestrials don't understand, like "I can come to your party if the winds are favorable." Why would it matter what the winds are doing? It doesn't, to the Terrestrial. The Aerial has to fly down from his home, so for him it does matter. On the other hand, you have a bunch of Terrestrials fully expecting an Aerial to use the ferryboat to get from one side of the river to the other, because 'that's how it is done'. The Aerial is pacing on the deck, frustrated at the slowness of the boat, and not understanding why he can't just spread his wings and glide across. Of course, if he tries to take off right then and there, he's going to rock the boat and make all the Terrestrials uncomfortable.
Now imagine that the Aerials are a small percentage of the population, and the majority are Terrestrials. You are more likely to have rules in place regarding airspace, schools judging you on how well you can swim (something Aerials don't tend to learn, because they were learning to fly instead), and a culture that regards flight as capricious and self-centered.
We could apply the same theory to humankind. The Terrestrials are what autism and ADHD groups call "neurotypical". They are the solid, organized, regimented people who build society by virtue of being in the majority. They have social rules and understandings, which they are practically born able to intuit. They can tell you what the social conventions are, from birthday parties to condolences, and how to perform your part in it properly. The Aerials are people who are wired differently. Terrestrials have struggled for centuries to define Aerials. Just recently, more people who used to be called ADHD are considered to have some form of autism. The term "aspergers" has also merged back into "autism" and spawned another term, "high-functioning". In other times and places they have been "eccentric", "insane but harmless", "shamans" or "witches", dreamers, "highly sensitive individuals", "Age of Aquarians", and so on.
I'd like to insert a disclaimer. I am not saying that "autism doesn't exist" or that it is not a problem. I am aware that there are Aerials who are nonverbal, who can't fight their way outside of their own heads, who engage in violent fits in response to bright lights and whatnot. On the other side, you need only read from the website notalwaysright.com to understand that there are neurotypicals on the extremist side as well. They just demonstrate it differently. However, there is an enormous struggle in the world of psychology and psychiatry to define and deal with the "high functioning" who do not respond to medication (or who can live fairly well without it), with the ones who are not called 'autistic' and then called 'autistic', and then 'aspergers', and then 'not aspergers'... How to differentiate them from the neurotypicals who have learned to be delicate in order to mimic a diagnosis, how to understand ADHD, what to do with a kid who seems very intelligent, but just can't apply it the way Terrestrials do. That's what I would like the term "Aerial" to do for me and others like me.
I also would like to take a moment to explain what "Terrestrials" and "Aerials" is not about. It's not about who is boring and who is artistic. It isn't about who is smart and who is stupid. It isn't about who has a stereotypical interest in engines and who prefers to work with people. It isn't even about fantasy versus reality, although Aerials tend to create fantasy and enjoy it, while Terrestrials may or may not enjoy it at all. For instance, I would say that Batman is an Aerial and Superman is a Terrestrial. Luke Skywalker is an Aerial and Leia is either Terrestrial or a mix. The main character of action-adventure stories is often a Terrestrial. Detectives may be either; Holmes was definitely an Aerial.
Now it gets interesting.
Being that we live in a Terrestrial society, we tend to judge things in terms of Terrestrial thinking. That's natural. In doing so, however, one of the big things that we say about Aerials is that they are socially inept. They don't follow social cues. They don't know how to interact with people the way the people expect to be interacted with. They ask weird questions, reveal more of themselves than they should in some areas, hide parts of themselves they shouldn't in other areas. At least, that's how the Aerial looks from the Terrestrial point of view.
In this area, I have a bit of a unique perspective. Usually, being that Aerials are rare, you will find one of two in a Terrestrial family. Both "Aerial' and 'Terrestrial' are, however, in part genetic. One classic stereotype (which has become a stereotype because it is often true) is that of a black sheep uncle and the nephew or niece who resembles him. That would be a key example of Aerial genetics within a majority Terrestrial family. In my family, however, we have an oddly strong concentration of Aerials. My father's side is strongly Aerial. My mother's is mostly Aerial within the recent generations, and mixed in some family lines as you start to move up a hundred years or more. My parents, my siblings, and I are all Aerials. In my husband's case, however, his Terrestrial father married an Aerial, and at least my husband (and perhaps his sister) is an Aerial. We have three children; all of them are unquestionably Aerials.
With all these Aerials, especially as my side tends to be close-knit and like to live near each other, I am slowly realizing that there is an Aerial social environment with intuited and unspoken rules, conventions, and practices. It is different than a Terrestrial social environment. I do not think it will emerge unless you have enough Aerials in one place. Once you do, however, you will find that they, like Terrestrials, will have ways to give offense, ways to avoid offense, things you are 'expected' to 'know' to do, and all of the other markers of any social environment. A Terrestrial in a group of Aerials who are no longer struggling to associate with each other the way they have been taught by Terrestrials will find himself just as puzzled, just as insecure, just as unable to intuit social graces as an Aerial at a Terrestrial party. Visit a family gathering of the sort that I grew up in, and you will find people asking each other favors that you're "not supposed to ask" and discussing topics that you're "not supposed to discuss" (according to Terrestrial norms), and yet simply intuiting which topics to avoid (which a Terrestrial might "clumsily" attempt) and at which point you simply do not push. A social group of Aerials understand why, to go back to my original fictional analogy, one Aerial cannot come or must return home early "because the winds aren't right".