Turns out, you might be a millennial and not even know it. Even if you’re approaching 40.

According to new research by CBS’ TV ratings guru David Poltrack and Nielsen Catalina Solutions, the youngest millennials should be graduating college this year — but that doesn’t mean they all consider themselves adults.

The median age of millennials is 30, Poltrack says — meaning that half are older and half are younger. And 30 happens to be the age at which millennials tend to self-identify as adults, Poltrack said. For these purposes, an “adult” is defined as “someone who has moved out of their parents’ home, has a job, and pays their own bills.”

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How did millennials start seeming so middle-aged? Poltrack says it because of “lazy” classifications that defined millennials as those 18-to-34. Poltrack, one of the most respected people in studying the demographics of TV viewers, uses designations like “millennial” to simplify who’s watching what.

He and the Center for Generational Kinetics both use the term to describe those born between 1979 and 1995, based on years prescribed by William Strauss and Neil Howe’s book “Generations.” It defines a generation as lasting for 18 years, and works forward from the giant Baby Boomer generation. Their kids, the next largest generation, are millennials. People born after 1995 are actually members of Gen Z.

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Why are millennials taking so long to grow up and move out? Some of it is their fault, some of it is their parents’ fault, and much of it is everyone’s fault.

For starters, the December 2007-June 2009 recession made finding employment harder — especially for recent college grads, many of whom happened to saddled with a ton student loan debt. High housing costs, meanwhile, reduced any stigma connected to living at home.

“More controversial is the whole idea that their baby boomer parents have really coddled them,” Poltrack told TheWrap. “They’ve made it too good for them. Why would you leave?”

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Well, at some point it’s pretty much to get married and have kids — to be an “adult,” in other words. That’s when people truly become valuable to someone like Poltrack, who wants them to buy a house and a few TVs — and tune in to CBS.

“Only now are they really coming into their own in terms of being major consumers of goods and services, and therefore a major economic component as well as a population component,” he explained.

The older people get, the more television they watch. And for CBS, the older TV viewers get, the more they watch “Blue Bloods.”

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So, millennials, go do some apartment hunting already — David Poltrack will help you pack.