I think that Tigerle has useful insights here, in multiple ways. I really agree with Tigrle that social skills can be learned past childhood: if one has has both the safety and the relationships in which to learn the skills. You have mentioned the reasons that may prevent you from doing that, which are not about your giftedness.

I also really did not learn many social skills during my schooling, due to more than one "E", and the intersection/s thereof. But I did acquire LATER,from good friends (and my now husband), many skills I had not learned during school, particularly in my 20s.

We ARE "all just people" as you say, no better, no worse, but it is a lot easier to have successful relationships with people who you connect with. And in having good relationships so learn skills for future social interaction. And we tend to connect with people who we have things in common, whether that is intellectual similarities or a favourite activity... Have you read Miraca Gross's "Exceptional Children", she makes a pretty compelling argument for the impact on social skills & self esteem of EG/PG children either being denied access to, or having access to like minded peers.

Each of the relationships in my life where I can clearly identify significant positive impact on my own social skills, were connections with people I have absolute confidence are/were equally or more gifted than myself (how hard it is for me to use the word gifted about myself). At times I have almost dejavu like experiences during an interaction and know that I am specifically using skills learned at a particular moment in time from a particular friend.

Back to the original question: the thing which I did not learn as a child, which causes me most difficulty now, is that I never learned to take notes. I had an exceptional memory. Anything I understood I remembered. Anything I read and understood, I not only remembered, but could usually also FIND again quickly: "That was on the top of the right hand page about 3/4 of the way through the book" I could then flop the book open, flick a few pages and produce the exact quote or diagram I was looking for (and would have remembered it correctly).

I now have multiple health issues, each of which separately have "brain fog" as a symptom... I am slow, my working memory is highly variable, and my actual memory is like swiss cheese. Sometimes I still remember things with absolute clarity, some things are completely blank, and others I can remember clearly with prompting (but not without). I have no idea when my memory will work and when it won't. Well I know it doesn't work if I am standing up, that's fun when meeting new people and talking with people in situations requiring standing.

I need to be table to take notes, but I also essentially have dysgraphia which magnifies the issue (and doubtless is half of why I never learned) AND I never learned anything about taking notes (WHEN should I think to take notes? WHAT would I note? How would I organise them? HOW would I remember that I had notes to refer to?). Trying to master these skills now, when I need them, and for the reason I need them, is very very difficult. I am trying. I have improved a little, not very much.

I need to be doing this at doctors appointments, in prep for doctors appointments, while at coffee with a group of mothers related to a child activity or school etc (so I can match those mothers to their children!).... You might class this as an academic skill, but it's something I need for activities of daily living and I don't have it.

Incidentally I have a friend who is VERY good at this and many of my improvements in this area have been assisted by seeing when she pulls out her diary and writes things down, and how she goes about it. Like pulling out her diary at coffee with a group of mums and writing down everyone's name, child & suburb at the start of the first gathering.