The New York Times
By Aurelien Breeden

Paris-You could say theirs is the Generation of Three E’s.

There is Erasmus, the European Union program that organizes and subsidizes student exchanges among universities across its 28 countries and elsewhere. There is easyJet, the budget airline that lets them hop between European cities as simply and cheaply as it can be to trek across town. And there is the euro, the currency used in most of the member countries.

Young adults are now grappling with what Britain’s vote to exit the European Union means for their profoundly European way of life. For them, it is perfectly normal to grow up in one country, study in another, work in a third, share a flat with people who have different passports and partner up without regard to nationality.

“It means that we are not going to be sisters and brothers of a big project,” said Antoine Guéry, 24, a Frenchman whose résumé and network of friends provide a crash course in European geography.

“At best, we are going to be allies” — friends, but no longer family. “It feels less like home.”

Mr. Guéry works at a public-relations firm in Paris but had been looking for job opportunities in London — an exercise he shelved immediately after the “Brexit” vote on June 23. His degree is from Sciences Po University in Paris, but he also studied at Stockholm University and Germany’s University of Potsdam.

It was in Stockholm that two German women, Carolina Leersch, now 26, and Kim Seele, 28, joined his inner circle. In Berlin, Mr. Guéry lived with Ms. Seele’s aunt, had an Irish boyfriend and befriended Lauren Muscroft, who is British, and Marion Desbles, who is from Rennes, France.

This group and others like it are, to be sure, a subset within a subset, part of a fourth E — the elite — who studied at the Continent’s top institutions and took advantage of the Pan-European doors open to them. Splitting Britain from the European Union may put a damper on future changes important to this globalized generation, like the move toward a single European digital market for movie and music streaming, and the end, by next year, of cellphone roaming charges when crossing European Union borders.

Days before the British referendum, Mr. Guéry, Ms. Muscroft and Ms. Desbles jokingly wondered, while waiting in the passport lines at the airport in Barcelona, Spain, whether Britons like Ms. Muscroft would soon be kicked out of the European Union lane.

Now, the friends are wondering whether their children will be able to benefit from Erasmus as they did. If their European health insurance cards will still cover them in Britain. Whether France might soon follow with a Frexit vote, the Netherlands with a Nexit, and who knows what else?

“My initial reaction when it happened was feeling like part of my identity had been stripped away,” said Ms. Muscroft, 24, who works in London for an online food-ordering site. “One thing I’ve always really felt a strong connection to, with Europe, is a unified sense of fate — the fact that we are all in this together, and that we benefit each other through this union.”

Perhaps the most profound force in creating this European identity was Erasmus, now called Erasmus+, which was created in 1987 and had supported 3.3 million students studying or training abroad by the end of 2013-14 academic year, according to a European Union report. (Yet, in the last five years, fewer than 5 percent of all university graduates in the participating countries were Erasmus students.)

But younger Europeans are more likely to report an attachment to the European Union than those 55 and over, according to the most recent Eurobarometer survey. In Britain before the balloting, surveys showed that 57 percent of voters ages 18 to 34 wanted it to remain in the bloc. (An identical percentage over age 55 supported the Leave campaign.)

In the vote’s aftermath, many young voices have expressed fear and despair.

“I’ve never been so angry,” Mr. Guéry said. “I was texting friends, people who did Erasmus, people who lived in Britain or Germany. We are disgusted that this might be the trigger for the destruction of the only good thing that these governments have done in 50 years: peace.”

It is still unclear what kind of relationship Britain will negotiate with the European Union, but trade is unlikely to screech to a halt and short-term travelers are not likely to face stringent visa requirements. As for the union’s Erasmus program — in which Britain ranked fifth two years ago for students sent abroad and fourth for foreign students taken in — nonmembers like Iceland, Norway and Turkey are already allowed to participate. Until Britain officially leaves the union, the program will continue there, too.

Britain had always stood apart in any case, having never adopted the euro or joined Europe’s passport-free Schengen zone.