A few years ago, Moya Sarner was in her kitchen when she went to throw out some rubbish. She noticed movement in the bin and realised it was maggots chewing away at discarded food.
She panicked and … she texted her mum.
This would be less noteworthy if Sarner wasn't 34 years old at the time.
In fact, at this point, Sarner, a UK author and psychotherapist, had a job, a partner and a house – the typical markers of adulthood.
Yet, the maggot moment left her feeling completely un-adult. It prompted her to consider what the label "adult" means, why she was uncomfortable with it and when she might be able to safely use it.
And when she started asking around, Sarner discovered there are many other grown-ups who don't feel as though they're fully fledged adults – and that this is not necessarily a bad thing.
'We don't just become adults when we turn 18'
Sarner says she felt a lack of resilience when she contacted her mother for advice about the maggots.
"I just had none of my own internal resources to rely on," she tells ABC RN's Life Matters.
She started to believe that the milestones like marriage, having children or buying white goods that often signify adulthood needed a shake-up.
"I started looking for a different kind of definition, one that is more around a sense of oneself, a kind of solidity and a separateness from others, and a sort of capacity to rely on oneself, and to look after oneself," says Sarner, who has written about her research in the book, When I Grow Up.
She interviewed people of all ages and backgrounds, as well as neuroscientists, psychologists and other experts. She learnt that the tenuous relationship with the "adult" label is a common one, crossing generations and class.
She also found that there is no concrete moment when a child brain becomes adult.
"We don't just become adults when we turn 18," she says.
Neuroscientist Sarah Jane Blackmore explained the similarities between the adult and adolescent brain to Sarner.
Sarner had assumed that there would be visibly distinguishing features on a brain scan, for example, with features that make it clear when you're looking at an adult or adolescent brain.
She was very surprised to learn that isn't the case at all.
"I actually learned that part of being an adult is being aware of what you cannot know, [and] being aware of your limits and the limits of our knowledge. You actually can't tell an adult brain just by looking at a brain scan.
"It's much fuzzier than that."
No job, no house, no adult?
The current climate of job insecurity and housing unaffordability is compounding the discomfort some have in applying the term "adult" to themselves, Sarner says.
She argues it is actually hard to be an adult when you can't get a job or when you can't afford to move out of home.
"I do think that sometimes there are conditions that facilitate growing up, that can be a fertile soil for growth and development: the capacity to live an independent life, to have your own space, to be able to support a family, to survive off a salary," she says.
The social problems that make attaining those things difficult can create a "kind of financial infantilisation", she says, that millennials in particular face.
"However, I do think that sometimes a kind of switcheroo happens, where people think [those external factors] constitute adulthood. And I don't think that's quite right."
Adulthood is more personal than that, Sarner says.
Rather than a house or fridge, a child or a job, she now sees the signs of adulthood as "the capacity to be kind, to be understanding and sensitive, tolerant of difference, to understand that things aren't black and white, there's nuance".
"These are all qualities that we develop if we do have the capacity to grow, and to inhabit more adult states of mind."
Furthermore, Sarner believes if you still think you're developing into an adult, no matter your age, you might just be getting something right.
"Most of the people that I spoke to in their 60s, 70s, 80s and 90s [said] there was still space for growth, still room for development, still something that didn't feel quite grown up," she says.
"And what I discovered is that, actually, if you see adulthood as a finish line, as a set of boxes to be ticked, then your life is all the poorer for it, because what really keeps us alive is continual growth and development.
"That's what keeps our brains alive and our minds alive and our lives really rich."
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