Adulthood is starting later and later for many young people today. TIMOTHY A. CLARY/AFP/Getty Images

An English teacher at Georgia Tech taught a course on "adulting," and found most of her students didn't consider themselves adults.

Many of her students said that adulthood starts when you have kids of your own.

Recent research has shown young people are putting off traditional milestones like marriage, having children, and home ownership.

The typical college kid may legally be an adult, but that doesn't mean they feel like one.

Rebekah Fitzsimmons would know - she's a postdoctoral fellow at Georgia Tech who taught an English course called "Adulting: Coming of Age in 21st Century America."

Over the course of the fall 2016 semester, Fitzsimmons had her students use digital media and historical texts to define what it means to be an adult in today's world.

Early on, Fitzsimmons learned that her students - who comprised the youngest members of the millennial generation - didn't consider themselves adults. That gave way to one of the main themes of the class: that adulthood starts later for young people today than ever before.

"In previous generations, that maybe happened a little bit sooner, a little bit younger, and there were clear demarcations for, hey, that person's a grown-up," Fitzsimmons told Business Insider.

Fitzsimmons said she had her students write essays about the milestones they thought marked a coming of age, and was surprised by the results.

"The vast majority of them said that they thought it was when you had kids of your own," she said. "It wasn't graduated from college, it wasn't getting your first job."

"I joked with him that my definition was, you're paying your own rent, you have your health insurance. That's what I think being an adult is. But they said, you know, once you have kids, that's it - you're definitely an adult."

And young people are putting off that milestone in record numbers. A recent report from the Center for Disease Control and Prevention said across the US, women in their 30s were having children at the highest rate in more than 50 years.

At the same time, the birthrate of women aged 15 to 24 experienced a nationwide decline, the report said.

Young people are waiting longer than their parents to get married, as well. According to a recent Gallup poll, 20% of Americans aged 18 to 30 are married, compared to 32% of Generation X members and 40% of Baby Boomers when they were the same ages. And one recent survey found a typical couple today is together for just short of five years before getting married.

Fitzsimmons said one of the reasons for the cultural shift is that college has become more accessible for young people - increased access to education means more people are putting off traditional milestones like home ownership, marriage, and having children.

But the economy looms large on their decision-making, too, she said, and many young people are feeling pressured to get a jump-start on their professional careers to justify the cost of education.

"Financial pressures are making the suburban home with a white picket fence, two cars in the driveway, two kids and a dog - it just doesn't seem feasible anymore," she told Business Insider.

"Right now my students are coming to college and they're not like, 'Oh, this is great, I'm going to kind of figure things out, I'm going to find my dream job.' They're like, 'I am sinking in the cost of this college education. It better get me back out.'"

NOW WATCH: Popular Videos from Insider Inc.