During the Middle Ages — long before deodorant — people often judged another's health by how they smelled. An individual who gave off "good air" was presumed healthier than one who reeked.
Over time, the odor eventually dissipated, but the metaphor lingered on. The French gave us de bonne aire , "of good air." That created a certain air about us (c. 16thC.) which originally, spoke to both "the atmosphere of a special place" as the air of an office and to a particular demeanor — an air of gentility or an air of grandeur.
Things got more complex when the odor, or lack of, same was taken as an indicator of the kind of person behind it, the assumption being that particular personalities were healthier (hence happier) than others.
Having an air about oneself began to convey a particularly positive disposition — gentle, mild, meek; gracious, kindly; courteous, affable; and "filled with gaiety of heart." It later described a gracious person or being; for men, meaning they were suave, urban, and sophisticated; for women, charming, confident, and carefully dressed.
It was never easy, however, distinguishing the real thing from something artificial and contrived. Around 1781, we started giving or putting on airs, or taking airs on, "assuming an unjustified aura of superiority." The results were predictable. People began getting a swelled head (c.1817) or a big head (c.1902), there being no other place to accommodate this exaggerated sense of self. All that air soon made began making people "high flown," which soon corrupted into "falutin," accounting for our highfalutin ways.
"High" in Old French was haut, synonymous with "proud," explaining our excellent taste as in haute cuisine, "fine gourmet cooking" and haute couture, "high fashion." Taking things too far, however, made us hawty, or haughty, "too proud," too high for our own good.
Being haughty as we were, we encouraged others to corrupt the word into the hoity in hoity-toity, showing us to be "pretentious and affected." How to explain the toity? Not to worry. It's just a little something thrown in for rhyme's sake.
It's not easy being hoity toity. All you need is a little humility from the Latin humus, "ground" or "soil," to bring you and your high-blown notions quickly back to earth; especially all you airheads (c.1980) out there.