Are you sure that the correlation between immune health during childhood and all of those positive attributes is causal?
Superficially, it seems more plausible that the causation starts much earlier, via mutational load or specific conditions during the gestation period. Though I suppose that it is also possible that health in the womb and health during early childhood could both effect adult outcomes.
Maybe I'm missing something, but I think you miss the most obvious way to improve your social skills: practice! Receiving positive social feedback is a skill and like all skills can be improved.
While there is a wide distribution in natural social competence, a large portion of the variance in social skills is attributable to how much time you spent interacting with other people during your formative years. The more time you spend with people, the less you have to think in social situations. You will have the experience to know what are the typical things t
... (read more)It's not clear what the performance metric is here or which things to focus on for practice. For instance, learning to read microexpressions in more detail can help reduce the long-run amount of social work required to manage an interaction, but at the cost of additional short-run cognitive load, and it has the risk of exacerbating problems instead.