There's a sensation you get when you hear the name of a group you're a member of. If someone says "Bostonian" or "liberal" or (sorry) "Patriots fan," my brain perks up a little. Oh, they're talking about me. Over the last few years, though, I've found I'm getting less and less of that ping from the term millennial.

Technically speaking, I'm definitely a millennial. I was born in 1983, which means I'm part of the generation, whether one uses the Census Bureau's definitio n (born 1982-2000) or Pew's (about 1981-1997). But the more I hear about millennials, the less I recognize myself. And I'm not alone on this front: In 2015, for example, Juliet Lapidos -- born the same year I was -- may have put it best in a column for the New York Times headlined "Wait, What, I'm a Millennial?" "I don't identify with the kids that Time magazine described as technology-addled narcissists, the Justin Bieber fans who ' boomerang ' back home instead of growing up," she writes. And I've had plenty of conversations with other people my age who feel the same way. Many, many people who are in their late 20s and early 30s simply don't feel like they are a part of the endlessly dissected millennial generation.

As it turns out, there are good reasons for this. Old Millennials, as I'll call them, who were born around 1988 or earlier (meaning they're 29 and older today), really have lived substantively different lives than Young Millennials, who were born around 1989 or later, as a result of two epochal events that occurred around the time when members of the older group were mostly young adults and when members of the younger were mostly early adolescents: the financial crisis and smartphones' profound takeover of society. And according to Jean Twenge , a social psychologist at San Diego State University and the author of " Generation Me: Why Today's Young Americans Are More Confident, Assertive, Entitled -- and More Miserable Than Ever Before ," there's some early, emerging evidence that, in certain ways, these two groups act like different, self-contained generations. ("Early" because there's still a fair amount we don't know about the youngest Young Millennials given how, well, young they are.)

Let's start with technology. Millennials, we hear over and over again, are absolutely obsessed with social media, and live their entire social lives through their smartphones. I tweet too much, sure, but I've never blasted a 'gram (did I say that right?); even thinking about learning how to Snapchat makes me want to take a long, peaceful nap; and I still feel bad whenever I haven't heard a distant friend's voice on the phone for a while. I miss out on nothing, in terms of real-world socializing, by sticking to Facebook and texting. I still prefer to read things -- particularly long things -- on paper. And again, almost all my friends (there are a few social-media-obsessed exceptions) feel similarly. On this front, we are decidedly different from Young Millennials, and to the extent the social-media-obsession stereotype is accurate, it simply doesn't apply to us in the same way.

Then there's the more substantive issue of how millennials (supposedly) live and structure their lives, and how they relate to the prevailing economic tides. Millennials are way less likely to follow "traditional" trajectories with regard to careers and marriage, both anecdotes and some data suggest. They often flit from job to job without staying in one place too long -- they're " The Job-Hopping Generation ," says Gallup -- and are much more likely, relative to previous generations when they were in their 20s, to live at home and to put off family formation for a long time. (It should be said that there's some controversy here -- just last week Pew released some numbers suggesting millennials aren't any job-hoppier than Generation X was at the same age.)

Again, this just doesn't resonate, either for me or for most of my friends who are my age. We're so normal! Yes, some of us have been hit harder than others by bad career luck or missteps, or by the massive national catastrophe of student debt, but for the most part we've had very "traditional" career paths. Now in our 30s, those of us who have had the most successful career trajectories are taking on many of the same young management roles that similarly privileged, middle-class boomers and Gen-Xers did when they reached those ages. I'm not married, but I'd say that more than half of my good friends are. Everyone's having kids; those who can afford it are buying houses. It's just bizarre to hear countless accounts of the unique nature of this generation -- my generation, supposedly -- and to then log onto Facebook and see so many people settling into exactly the lives expected of people in their 30s. Nothing about our collective experiences as adolescents and young(ish) adults, overall, feels that different from the stories we've heard about how members of past generations grew up and carved out their personal and professional niches. (I've already used the term privileged in this paragraph, but it's worth pointing out that privilege colors this entire discussion: Suffice it to say there are plenty of economically disadvantaged people who never have a fair shot at a good, remunerative career of any sort. In terms of my own life and the lives of my friends/colleagues, I can only speak to one, mostly middle-class slice of the millennial experience.)

To be sure, the dissociation I'm feeling from my own generation is partly an inevitable artifact of the artificial way we construct generations in the first place. Generations are usually defined as anyone who was born within a span of about 18 years or so, and a lot happens in 18 years. The baby-boomers, for example, consist of those who were born from 1946 to 1964, or thereabouts -- their oldest members were born not long after America's world-historical triumph in World War II, while their youngest grew up during the 1960s, a period of crescendoing turmoil in American civic and political life. The youngest and oldest boomers grew up in very different worlds.

But this time around might be different. When I emailed Twenge to ask about the possibility of meaningful differences between older and younger millennials, she quickly highlighted those two events: the financial collapse of 2008 and the rise of smartphones around that same time (the iPhone was introduced in 2007). Their impact can't be overstated, and because of precisely when they hit, it really might be the case that in 2017 a 33-year-old is more different from a 23-year-old than at any other point in recent history. (That could explain why Twenge is working on a book about those born in the 1990s, and how they're "vastly different from their Millennial predecessors," as the publicity language puts it.)

Take the financial crash. Many Old Millennials were either already in the workforce by then, or close enough to entering it that we were able to "sneak in" before the crisis had fully unfurled itself. Which means we were raised and educated during a period in which we were promised that if we followed the rules in certain ways, there would be gainful employment waiting for us in our early or mid-20s -- which there often was. The same definitely cannot be said of Young Millennials. The crisis permanently rejiggered the world for them. They grew up, like us Old Millennials, assuming that things would more or less work out if they followed the rules laid out by adults, only to have the rug pulled out from under them entirely during a very formative period in their lives.

This is a big deal, to have your expectations about your life so violently reoriented as a teenager or young adult. And while plenty of older millennials were affected, too -- especially as the ramifications of the crisis rippled outward -- the crisis really did hit Young Millennials in a different way. "Early millennials grew up in an optimistic time and were then hit by the recession, whereas late millennials had their worldview made more realistic by experiencing the recession while during their formative years," explained Twenge. According to Twenge, this has led to certain differences between older and younger millennials that manifest in the data. For example, she's found some evidence from survey data that younger millennials "are more practical -- they are more attracted to industries with steady work and are more likely to say they are willing to work overtime" than older ones. Us Old Millennials could afford to develop views on work and work-life balance that were a bit more idealistic.

Then there are smartphones and social media, which hit the two halves of the generation in massively different ways. "Unlike [Young Millennials]," wrote Lapidos, "I am not a true digital native. The Internet wasn't a fact of nature. I had to learn what it was and how to use it. I wrote letters home when I was at summer camp. I didn't have a mobile phone until I was 19." For us Old Millennials, the social aspects of our middle- and high-school-years were lived mostly offline. Sure, AOL Instant Messenger was a pretty big deal when it first caught on, but most of us didn't even have cell phones until college, and smartphones until after. Think about all the stuff you go through between the ages of 12 and 22 in terms of your development as a person. Now think about how many of those experiences are affected by the presence or absence of a cell phone and social media.

According to Twenge, there's a bit less hard data on how smartphones drove an intragenerational wedge than there is on the subject of the Great Recession -- she's working on this question, but doesn't yet have hard answer. But it would be shocking if this technological revolution didn't carve out some important differences between Old and Young Millennials. While there are certainly plenty of overhyped, underscientific opinions about how social media affects people, there's little question that it has some effect (there is some evidence that extensive Facebook usage is correlated with unhappiness, for example, including some fairly meaty recently published research ). Twenge said that she thinks the fact that younger millennials spend so much more time on social media might be able to explain, for example, why they seem to be more susceptible to certain forms of psychological distress, including depression. That said, "What we don't have yet is research connecting these two areas of research" -- that is, research making a stronger, more rigorous connection between generational differences between social-media use and rates of psychological distress.

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What all this suggests is that there's very little to be gained from lumping together all millennials in one group. Again, to a certain extent you can say this about any generation, but some genuinely unique and unusual stuff helped create the current divide. While the Old and Young Millennial categories aren't carved in stone, and there is certainly some overlap (especially for those who were influenced by older siblings), it doesn't benefit anyone to act like a 33-year-old and a 23-year-old came up in the same general climate, or with access to the same types of world-altering technology. No: These are profound differences. For the good of both us Old Millennials and our Young Millennial siblings and friends, let's stop acting like we're all in the same boat.