The vapidity and social-emotional stunting of the Millennials has become clearer over the past five or so years. Earlier than that, most of them weren't really old enough to judge, and during the mid-2000s everyone was a bit more outgoing and fun-loving, which disguised their fundamentally avoidant nature.
It looks like social avoidance goes up in falling-crime times, as people see less reason to band together, look out for each other, and so on. And Millennials indeed grew up in such an environment.
A helpful way to look at this generational gap is to ask if it's happened before -- not just a gap, but one with these particular features. We need to ask what earlier generations were like ours, and which ones were like theirs. Did they clash the way we are now?
Earlier I showed how to move back and forth between recent historical periods in America by asking where they were at in the crime rate cycle, since that is the strongest influence on the zeitgeist. The two peaks, one in 1933 and the other in 1992, are separated by 59 years. Thus, you can take a recent year and move back 59 years to find a similar year in the past, or take a year far in the past that you don't know about and add 59 to arrive at a similar year that you'll have a better feel for.
Millennial births begin in 1985. Moving back 59 years, we find their ancestors born starting in 1926 and lasting for awhile after, i.e. the Silent Generation (whose last births are in the mid-'40s). Several older generations look at Millennials like they're from another planet; again just subtract 59 from your birth year to find out who your ancestors would have been.
One of the most vivid portrayals of how bizarre the Silent Generation seemed to those who were older can be seen in the movie Network. The least sympathetic characters are played by Faye Dunaway and Robert Duvall. Although they aren't playing themselves, they are still playing someone close to their own age, which is what matters here. Dunaway was born in 1941 and Duvall in 1931, so both are Silent Gen members.
Their dismissive-avoidant style of social and emotional attachment, combined with their numbness to and lack of yearning for anything eternal, moral, or sublime, clearly separate them from the more sympathetic characters played by William Holden and Peter Finch. They were born in 1918 and 1916, respectively, so their descendants are 1977 and 1975 births, making them Generation X. Screenplay writer Paddy Chayefsky was born in 1923 and director Sidney Lumet in 1924. So their descendants would be 1982-'83 births, part of the small cohort between Gen X and Millennials, though more similar to the former.
The conflict between the Holden-Finch and the Dunaway-Duvall generations pervades the movie, but it's revealed in its rawest form during a breakup scene between Holden and Dunaway, who had been carrying on a May-December affair marked by her inability to connect emotionally. YouTube won't let me embed the clip, but click on the link:
Network breakup scene
Notice that the pre-Silent Gen figures weren't born in the 1900s or early 1910s. Those people, having also come of age during rising-crime times, would have resembled Holden, Finch, Chayefsky, and Lumet, but they wouldn't have been close enough in age to the Silent Generation to have been familiar with all of their gross and subtle differences. It's the same today with Millennials. Few Boomers notice, as most of their relationships with them are parent-child. Generation X and Y, who interact with them more and outside of family contexts, spontaneously remark, in detail, about how dorky and stunted the Millennials are.
Chayefsky and Lumet weren't even adolescents during rising-crime times, which suggests that even making it through primary school age in such an environment goes a long way to making you human. That shows up in today's world too, where Gen Y (i.e., born between '79 and '84) aren't quite as developed as the Boomers and X-ers, but still closer to them than to the Millennials, who are a quantum drop below.
We must be forming our expectations of what the world is like, and unconsciously molding our minds to reflect that, even as toddlers and elementary school students. Maybe even in infancy, noticing how expressive people's faces are around each other, how open vs. restricted their vocal inflection is when they talk to each other, how much pheromones they're pumping into the air, and who knows what else.
It looks like most of the learning is done from age 7 and after, given that Millennials born in the later '80s, and so who were toddlers during the end of the rising-crime period, look just about the same as the ones born after the early '90s peak, and so who have lived entirely within falling-crime times. Learning in infancy and toddlerhood probably makes a difference only if it persists through the elementary school and early adolescent years. Otherwise, if there's a fundamental shift in the environment during ages 4-7, the mind says it's not too late to change, and unlearns all that now irrelevant -- even misleading -- information it had processed earlier on.