I can’t remember a time when I didn’t know that I was vulnerable. From childhood on, I felt stress as acutely as a needle puncture – the familiar tightness in my ribcage, the trembling in my upper arms. In an attempt to dull the pain, I’d obsess endlessly about the current subject of my worries, whether it was a guy who’d rejected me or the strange bruises that had appeared on my legs overnight. As an adult, I learned that ruminating – lingering over problems like a cow chewing cud – was linked to the depression and anxiety that I suffered in repeated bouts. But knowing this wasn’t enough to halt my obsessing. Something in me believed it was the way through the crucible, and stopping felt like relinquishing all control.

Still, I’ve long known that not everyone responds to stress the way I do. I see the evidence every day in my own home. My husband, the descendant of laid-back Scandinavians, seems largely impervious to stresses and misfortunes. When something bad happens, he might withdraw into himself for a time, but he tends to bounce back within hours or, at most, days. I think of him as a sturdy wagon, one that keeps rolling along, no matter the condition of the road. Then there’s the author Kelly Hayes-Raitt, who has faced various slings and arrows through the years. Post-9/11, her consulting business went bottom-up, leaving her $90,000 in debt. After that, she ran for political office in Santa Monica in California, and lost after enduring multiple rounds of character assassination. But through it all, she says, she’s never felt particularly anxious, depressed or otherwise unmoored – and she’s never received any kind of psychiatric diagnosis.

I regard such temperamentally blessed people with awe, and I’m more than a little curious about the source of their endurance. Why is it that, after what psychologists call an ‘adverse event’, I have a near-irresistible urge to wallow and curl into myself, while the temperamentally blessed deploy their emotional stabilisers and sail on blithely? Is it genes, upbringing or something less easily defined? And should we seek to follow their example – or are emotional ups and downs a natural and integral part of a life well-lived? Is it even mentally healthy to stay so even-keeled when chaos descends?

Jonathan Schaefer, a graduate student in psychology, is among the researchers who have begun to address such questions. Soon before Schaefer arrived at Duke University in North Carolina, his advisor, the psychologist Terrie Moffitt, published a paper showing that when people are assessed regularly for mental-health problems, their incidence of common mental illnesses was far higher than previous estimates. By age 32, more than 40 per cent of the study participants had had at least one episode of depression, while nearly 50 per cent had suffered from anxiety. Schaefer remembers digesting the paper and finding it intriguing. ‘OK, so if this proportion of the population is experiencing different disorders, who’s left over?’ he thought to himself. ‘Who actually is making it through the first half of their life without a diagnosis?’

To find out what made these diagnosis-free people distinct, Schaefer turned to the same subjects whom Moffitt had studied – the Dunedin cohort, a group of 1,037 people all born in the same town in New Zealand between April 1972 and March 1973. Every few years since their birth, the members of the cohort have returned to Dunedin to undergo batteries of medical tests and interviews. Assessors evaluate, among other things, their reproductive health, their social aptitude and their current mental state. To date, the study has retained about 95 per cent of its original subjects and, if all goes as planned, they will submit to periodic testing for the rest of their lives.

As Schaefer dug deep into the Dunedin files, one thing that jumped out at him was that the vast majority of cohort members had met criteria for a mental illness at some point in their lives. In the turbulent years leading up to middle age, 83 per cent had suffered from either short-lived or longer-lasting mental disorders. ‘Experiencing these conditions is actually the norm,’ Schaefer says. ‘It’s kind of weird not to.’

The discovery that mental illness was far more the rule than the exception made Schaefer more eager to understand who the remaining 17 per cent of the population were – what was it about their approach to life that preserved their mental health? He presumed, at first, that people who’d been born to wealthy parents or who’d maintained good physical health might end up in the temperamentally blessed group, since poverty and ill health are clear harbingers of mental disorder.

That didn’t turn out to be the case, though. Unsurprisingly, the temperamentally blessed in Schaefer’s study tended to be people whose first-degree relatives were never diagnosed with mental illness, suggesting that their ongoing buoyancy was, at least in part, genetic. But people who enjoyed enduring mental health weren’t unusually rich, physically healthy or intelligent. ‘We expected that they would be from well-off families, so would be protected from stress by money and financial resources, but they were not,’ says Moffitt, who was a contributing author on Schaefer’s recent paper. ‘And we expected they would be very high-IQ kids, so would be protected by being extra-smart and able to think their way out of problems, but they were not.’

Enduring mental health, it appears, isn’t as much about surface advantage as how you play the hand you’ve got. In Moffitt’s view, the temperamentally blessed members of the Dunedin cohort ‘embrace life, get active, and get involved, but when bad things happen they don’t over-react. They really just remain calm and get on with it,’ she says. They manage stress, it appears, by not focusing intently on their problems, and also by surrounding themselves with supportive others. ‘They like being with people, and they reach out to build a social network. As loved ones, they are steady and dependable, not touchy or thin-skinned. They don’t often quarrel. They are pretty tolerant of other people in their lives.’

‘We could copy the lifestyles of people with enduring mental health to see how to live well’

Because the Dunedin study has tracked subjects from birth onwards, we know that these distinctive personality traits often show up by the elementary-school years, Schaefer says. Children who have more friends at an early age are less likely to experience an episode of mental illness as adults. ‘This is a process, a way of being, that emerges pretty early on.’

If genetics play a key role in temperament, and if many of the traits that reinforce temperament are baked in early on, does it still make sense to try to foster an environment that promotes temperamental stability? Moffitt says yes – and that one possible approach would be to recreate the social and emotional milieu that the temperamentally blessed seem to inhabit. ‘I think we could copy the lifestyles of people with enduring mental health to see how to live well.’

Almost invariably, such people boast a dense web of communal ties, underscoring the role of supportive networks in mitigating stressful life events such as a job loss or a divorce. (To be sure, these networks might help some more than others; though my husband and I share most of the same social contacts, our responses to stress remain distinct.) Likewise, a live-and-let-live attitude is probably teachable, at least to some degree. Dialectical behaviour therapy (DBT) – designed to teach emotional regulation – is geared toward boosting clients’ tolerance and acceptance of others. Studies show that this therapy improves their functioning in the real world, inching them closer to the temperamentally blessed category even if they don’t always reach it.

Scientists could someday emulate the biology of the temperamentally blessed as well. If functional MRI studies show that they have discrete patterns of brain activation, and if DNA sequencing reveals distinct stretches of genetic code, those traits could supply clear blueprints for drug-makers. The landmark antidepressant Prozac – first viewed as a potential high blood-pressure treatment – was a partially accidental stride in this direction. It happened to leave more serotonin floating in the synapses between neurons, fuelling the kind of mood benefits that are often the birthright of the temperamentally blessed. Imagine what a more deliberate search, one that targets specific neural pathways from the start, might turn up.

But is complete freedom from mental disorder the unalloyed triumph it first seems? To be sure, severe mental disorders such as schizophrenia and psychosis have very little adaptive value at all. But certain, more common conditions, especially depression and anxiety, sometimes make a bleak kind of evolutionary sense: they’re screaming neon warnings that there are urgent problems in your life that you need to address.

And depressive or anxious thoughts do drive effective problem-solving in a variety of situations, according to the psychologist Paul Andrews, now at McMaster University in Ontario. Because depressed people’s thinking style is highly analytical (in other words, obsessive), they incisively evaluate the pros and cons of potential solutions. ‘Depression seems less like a disorder where the brain is operating in a haphazard way, or malfunctioning,’ write Andrews and his colleague, J Anderson Thomson Jr, in a 2009 article for Scientific American. ‘Instead, depression seems more like the vertebrate eye – an intricate, highly organised piece of machinery that performs a specific function.’

From that standpoint, the 50something divorcee who weathers financial ruin with a smile seems like the oddball, not her despairing counterpart. While people’s genetic vulnerability to mental disorder differs, most of us are at higher risk when life heads south in one way or another. The temperamentally blessed seem unusually immune to circumstance; either they do not feel the sting of defeat as acutely, or they have found reliable ways to blunt it. They look strong to others because they do not react intensely to calamity. But it’s worth asking whether that very lack of intense reaction might betray a covert psychological weakness – a tendency to stand still when dramatic movement is called for.

In fact, the burgeoning field of post-traumatic growth research suggests that people reap profound benefits when they risk dramatic movement in the face of mental anguish. ‘I think you do see that,’ Schaefer says. ‘Tackling a particular problem, and then having navigated that successfully – that can be a big thing.’ In a study at the University of L’Aquila in Italy, earthquake survivors who suffered moderate depression in the disaster’s wake reported significant post-traumatic flowering. They forged stronger relationships with others, professed more faith in their personal strength, and attained a clearer sense of their life’s mission.

My own experience echoes these findings. After emerging from my first episode of depression, I understood far better what other depressed people were going through. Since then, it’s felt natural to commiserate with them and share my own experience, connecting with them on a deeper level than before. I’m convinced that without the discovery that my own suffering activated my empathy and my desire to help, I never would have written my book What Makes a Hero? (2013), on the science of selflessness.

However even-keeled, the temperamentally blessed don’t score much higher on life-satisfaction scales

In a society where mental disturbance is endlessly pathologised, it’s easy to conclude that the pinnacle of mental health is the absence of illness. This idea leads us to lionise those who steer clear of the ‘disease’ label. But a broader, more Jungian conception of mental health – one that encompasses the entire human meaning-making process – includes emotional setbacks, even profound ones, viewing them as invitations to engage in the ongoing project of destroying and rebuilding the self.

If the temperamentally blessed aren’t experiencing the degree of emotional upset and struggle that’s natural in difficult times, does that mean there’s something fundamental that they’re missing out on, some sort of existential tempering? That’s an open question, from a scientific perspective as well as a philosophical one. What does seem clear, though, is that being temperamentally blessed is not the same as being happy in a deeper sense. However even-keeled they might be, the temperamentally blessed don’t score much higher on life-satisfaction scales than those who are not as blessed. ‘There’s more to life than not experiencing mental disorder,’ Schaefer says. ‘There are some people in the enduring mental-health group who rate their life satisfaction as pretty low.’

We also know that you don’t have to clear the bar of being temperamentally blessed in order to reach fulfilment. Flourishing – experiencing positive emotions, general enthusiasm about life and a sense of purpose (the state that Aristotle called eudaimonia) – ‘is completely separate’, Schaefer says, and ‘not terribly highly correlated with symptoms of a mental disorder’. In other words, you can suffer mental illness, even repeatedly, and still retain a sense that life is meaningful; as Walt Whitman put it: ‘the powerful play goes on, and you may contribute a verse’.

Still, there’s no denying the toll that full-blown mental illness takes on one’s body, mind and ability to work toward goals that promote flourishing. I know firsthand that not all pathology is productive. And while I’m grateful to have broadened my capacity for intimacy and empathy, I don’t want to keep flagellating myself with lessons I’ve already learned.

I yearn, now, to enter a state of relative emotional maintenance, and that’s where the example that the temperamentally blessed set can be a force for good. They seem to have a knack for anticipating and avoiding the most immobilising inner tempests – an approach worth road-testing. After Hayes-Raitt’s political aspirations went bust, she decided to travel to the Middle East to aid refugees there. ‘I worked with people whose losses far outweighed my own to help put my own loss in perspective,’ she says. In so doing, she retained her sense of agency and made a meaningful contribution, reaching much the same flourishing endpoint that many people reach in the aftermath of depression.

We’re well-equipped to break and mend, mentally as well as physically

So while the temperamentally blessed might not have the same access to transformation that arises through emotional trauma, they can still engage full-tilt in the project of building out the self to make it whole. They might just need to be willing to adopt a new approach to life without the knife’s-edge motivation of knowing that the old approach is intolerable.

This year, the subjects in the Dunedin study will finish turning 45. This means that Moffitt, Schaefer and their colleagues are in the midst of collecting another round of data – and checking in on the temperamentally blessed members of the cohort. For the first time, Schaefer plans to carry out functional MRI brain scans of everyone in the ‘enduring mental health’ group to detect neural activity that might distinguish them from their peers. Schaefer is also keen to see whether the number of people who qualify for the group holds steady or keeps falling. ‘My strong suspicion is that the proportion of folks will continue to shrink. It’ll be interesting to see if anyone’s left by the end.’

If we’re tempted to think that there is anything secure or unassailable in being temperamentally blessed, the way that the group’s ranks keep thinning with age dispels that notion. Schaefer’s research reveals that mental disorders are exceedingly common and often transient, a finding he hopes will reduce the stigma surrounding mental illness. To me, though, what that finding declares most loudly is that we’re well-equipped to break and mend, mentally as well as physically. The cycle of the hero’s journey, that powerful monomyth that transcends time and culture, features a protagonist who weathers deep adversity, emerges stronger from the struggle, and draws on that earned resolve in conquering further challenges. Being temperamentally blessed, by contrast, is an endowment for which the bearer cannot take full credit. If you sail over the same waves that fell others, by all means, celebrate your good fortune. But it’s no guarantee that the race will be yours.

This Essay was made possible through the support of a grant from the Templeton Religion Trust to Aeon. The opinions expressed in this publication are those of the author and do not necessarily reflect the views of the Templeton Religion Trust.

Funders to Aeon Magazine are not involved in editorial decision-making, including commissioning or content-approval.