Jeanne Marrin, 48, comes from what she calls an “HR family.” She runs a human resources consulting company out of Manhattan, pinch hitting for big nonprofits when they need help hiring and setting up procedures. One of her sisters helps with that business, and another sister runs her own workplace culture consultancy in Washington. Marrin’s father has managed HR departments as a vice president of finance, and her mother is an assistant vice president of employee relations at a large non-profit hospital in the Bronx. Her brother is the black sheep, running a moving company in Raleigh, N.C.

“Jill and I do his HR when he lets us,” she joked in an email.

As it happens, Marrin’s HR family is also a signifier of a big shift in the HR world. She and her sisters all went to college and got advanced degrees, almost as the price of entry. Her mother, however, never even graduated from college. Instead, she started working for a college in administrative support, before following a boss to the hospital and moving up the ranks. “I think somebody brought her there and believed in her,” Marrin says. “She has maybe one college class and in my opinion can do the job better than me.” 

Today, that might never have happened. More and more employers are requiring bachelors degrees for positions that years ago wouldn’t have needed them, shutting off access for the unmatriculated. Forget the “skills gap.” According to a new report from the career data analytics service Burning Glass, there’s actually a  “credentials gap” for training and development specialists: While only half the people currently in that role have undergraduate degrees, 75 percent of online job postings list a BA as a requirement, leaving a gap of 25 percent.

The gap is similar in administrative support positions, where Marrin’s mother started out; 45 percent of listings require college degrees, compared to the 20 percent of current job-holders who have one. It exists across a broad swath of job categories, from factory supervisors (a whopping 45 percent credentials gap) to insurance claims clerks (24 percent). And sometimes, it even means that employers are willing to wait longer to fill the job.

What’s going on here? Can in be that those jobs are actually more complicated now, requiring the skills that an undergraduate education might confer? Or is something else happening?

Burning Glass was able to break down the reasoning that might be at play, by comparing the actual job descriptions of those listings that required college degrees with those that did not, as well as how job descriptions change over time. In some fields, like electrical drafting, the job has generally gotten more complex and requires a broader skill set as technology changes; there’s also more demand for drafters overall, and salaries have increased accordingly.

In others, like tech support, jobs that required bachelors degrees differed not at all in their essential functions from those that did not. In those cases, Burning Glass suggests, employers might be using the BA simply to narrow the pool — every new listing is answered with a flood of applications, and it seems as good a criterion as any to conduct a version of HR triage.

Employers have to be careful about this. Adding job requirements that aren’t specifically relevant to the job can inadvertently block certain demographic groups more than others, which might run afoul of the federal Equal Employment Opportunity Commission. This happened during the recession, says Maryland HR consultant Christine Walters, when some employers started saying that they would only consider applicants who had jobs already — i.e., the unemployed need not apply.

“The reason we did that was because we need some parameter to cull through 200 responses to each vacancy,” Walters says (speaking of other employers, not her own clients). The strategy was quickly kiboshed as discriminatory. “When we say something’s required, we really need to make sure it’s legally defensible.”

Of course, most employers would contend that the soft skills you’re supposed to gain in college can only help with any kind of job. “You learn time management, how to work in teams, use social skills,” Marrin says. “And you know what? You’ve committed to something.” (Today’s younger applicants can be shockingly flaky, she says.) She recalls talking with an executive assistant (credential gap: 46 percent!) to the CEO of a large nonprofit who was recruiting for an assistant of his own, and asking why he’d asked for a BA on the job application. “He said it screens candidates out, and they generally have better tech skills,” Marrin says. 

Taken in combination, both of those forces — the increasing relevance of BAs to formerly simple jobs that have gotten more challenging, and the use of the BA as a filtering mechanism — explain why going to college still pays off. It’s not necessarily that the job market has gotten a lot better for BA holders. It’s that it’s gotten so much worse for people without them, as New York Fed researchers described last week. That effect shows up vividly in the Organization for Economic Co-operation and Development’s recent comparison of earnings by educational status in its member countries: The United States has a higher percentage of people without college degrees making below half the median income than anywhere else.

But if four-year degrees aren’t strictly necessary for all these jobs, why aren’t employers looking for more applicants who’ve gone the financially conservative route and gotten a vocational certification?

Looking at the evidence of BA inflation, Burning Glass CEO Matt Sigelman thinks there’s a credibility problem with programs that take less time and effort. “That tells me that what we’re really seeing here is less about the BA representing things that employers are really looking for, than other alternatives don’t,” he says. “Employers are clearly skeptical that an associates degree really meets their needs.” (It’s worth noting, though, that in professions where the professional degree is directly relevant to the job description, like nursing, the credentials gap is zero.)

That’s not good news for people who don’t want to take on tens of thousands of dollars of debt when there isn’t a guaranteed job at the end of it. And it also might make bad hiring policy: It’s possible to look over that one person who might be perfect for the job, even if they don’t have any letters after their name.

Like Marrin’s mother. Now, Marrin herself would be much more qualified for the job her mother worked her way into, even though she says she got her master’s in business administration after years as an HR professional just to stop a mentor from bugging her about it.

“To keep her quiet, I did it,” Marrin says. “It has helped. People are impressed by it, and sometimes in my head, I’m like, really?”