People on long-term foreign assignments often find it hard to adjust once they return home. Many leave their company within a few years, and some leave the country entirely.

Editor’s Note (27 December 2016): Through the end of the year, BBC Capital is bringing back some of your favourite stories from 2016.

After 15 years, and a life on the road that took her to Japan, Singapore and Australia, Helen Maffini felt it was time to return home to Canada. But, it took just a fraction of that time for her to realise she had made a mistake.

“We moved [back] to Canada in 2013 because we thought we wanted to settle down,” she says, via email. “We realised after a year, we did not! Me, especially. I found it hard to fit in again, I felt very different and things had changed a lot. We found the long winter very hard and it was pretty quiet compared to where we have lived before.”

Such long absences can play havoc with a person’s sense of identity, a feeling that is intensified by the length of time away and how often they visit home

Perhaps unsurprisingly, Maffini, 46, an education consultant, this month, moved to Cambodia, where her husband, an Italian chef, is taking up a new position.

Maffini's experience is not unusual, particularly as the expat demographic has shifted over the past 20 years. Traditionally, an expat posting involved a professional being transferred to an international office by their company for what would typically be a one-off three-year deployment. A lucrative package of incentives would often sweeten the deal.

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But recent surveys show the expat profile is changing. Expats are now as likely to be Asian, as Western European or North American, according to one report. And expats are taking a string of shorter, back-to-back assignments or agreeing to longer-term deployments. People are also finding their own jobs abroad. Whether by choice or design, many find themselves living away from home for a decade or more.

Repatriation upheaval

But there are downsides. Such long absences can play havoc with a person’s sense of identity, a feeling that is intensified by the length of time away and how often they visit home, according to Nicola McCaffrey, a psychologist based in Stavanger, Norway. Some long-term expats can’t adjust to their new life in their old home and struggle with reverse culture shock. In some cases, they return to the road, unable to pick up where they left off.

The longer I am gone, the less attached I feel to any nationality - Helen Maffini

“The longer I am gone, the less attached I feel to any nationality,” says Maffini, who has dual Canadian-British citizenship.

Even for expats who take shorter assignments, returning home can prove an enormous upheaval. The vast majority of companies (78% according to Cartus’ 2016 Global Mobility Policy and Practices survey) don’t track staff retention following repatriation, but of those that do, 52% said that between zero and 10 employees left within a year or two of returning home, and 24% said between 11 and 30 quit.

“Many people start to repatriate when they want to settle down and have a family,” says London-based career performance coach Nikki Thomas, who spent two years working in Hong Kong. “It is the idea of bringing their children up in the same country [where] they were born, and giving their child the same passport – their identity. It’s also that you see your homeland through rose-tinted glasses after you leave, and as the generations get older you want to be ‘home’ for your parents.”

The problem is that those glossy expectations may not measure up to reality. The world keeps moving while you are gone. Thomas recalls the shock of the vote for Brexit to the British friends she’d made in the territory.  “I think it scared them; that their home wasn’t how they’d left it,” she says.

Although many organisations spend a considerable amount – sometimes as much as three times an employee’s annual pay – on expatriation, the return process is often whittled down to the simple logistics such as flights, moving costs and school fees.

The well-being of the employee and their family, even though they may have been away for five years or more, is rarely considered.

Living and working abroad can change the employee and their family members profoundly, and in a way they could never anticipate

“It’s something that is hugely overlooked, and something that seriously needs to be looked at,” says Thomas. “Many people who come home want to leave again, and that is primarily because of the lack of support.”

Worse, employees may have taken an international assignment thinking it would fast-track their career back home, only to find themselves in a role that makes little use of the skills they acquired abroad.

Reverse culture shock

Expats too often underestimate the transformational aspect of living overseas for an extended period. “Living and working abroad can change the employee and their family members profoundly, and in a way they could never anticipate,” says Jenny Castelino, director of intercultural sales and account management at Cartus.

Although jobs may be a factor in the decision to repatriate, particularly in these troubled economic times, many expats return to their homeland to be closer to family.

It’s the reason conservation biologist Mei-Ho Lee, 39, returned to Malaysia in 2009 after a decade in the United States.

While Lee had prepared for her return for a year, the emotional upheaval still came as a shock. For the first few months, she retreated to her parents’ house, swapping the chaos and noise of New York and her laboratory at Columbia University for the slower-paced city of Ipoh in northern Malaysia.

KL was a completely different place to what it had been before. I couldn’t recognise anything - Mei-Ho Lee

“The first few weeks were like hibernating,” she remembers. Then, once her job was confirmed, she moved to Kuala Lumpur, Malaysia’s busy and congested capital.

Lee had interviewed for a position with an American conservation organisation while in the US, but could only start work once the funding for the role had been confirmed.

“KL was a completely different place to what it had been before. I couldn’t recognise anything; any roads at all. And I didn’t have a car so it was very difficult. I missed the public transport in New York.”

Working practices in her homeland also came as a shock. “I have to switch to Asian mode,” says Lee.

Third Culture Kids

And then there are the expat children.

Karen, a British citizen now in Malaysia, who prefers to be known only by her first name because her husband works for a large multinational, recalls their 22 years on the road became more difficult as their children got older. Both are now at university in the UK. Having never lived in Malaysia, they don’t see it as home, and their actual home in Europe is rented out. “Their home is out of a suitcase,” Karen says.

The term Third Culture Kids describes children who’ve spent much of their formative years outside their own country

American sociologist Ruth Hill Useem coined the term Third Culture Kids (TCK) to describe children who’d spent much of their formative years outside their own country. Her research was triggered by the experience of her own children growing up in India, where she was posted on a research project in the 1950s. A typical TCK will tend to have multiple answers to the question of where they’re from, friends from numerous countries and, often, the ability to speak more than one language.

Maffini describes her children as “resilient” but says they’d probably be hard-pushed to define the idea of home. She has written a book, Sammy’s Next Move,  to help guide other children through the realities of a life on the move, and the notions of home and identity. The main character is a snail who takes his home with him wherever he goes.

In fact, Maffini dates the start of her own expat life to when she was 15 and her father accepted a job at a research laboratory in Japan. So it's not surprising that she's chosen a similar life for herself. Her own daughter, now 20, is studying hospitality in Ottawa and, like many TCKs, appears to have inherited her parents’ restlessness. She has no plans to stay in Canada. Her ambition is to travel the world.

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