Many of the current generation of recent over-18s do not feel like an adult, according to a survey by building society Nationwide, and those commenting on the BBC News Facebook page seem to agree.
Nationwide's study of 2,000 over-18s found more than one in 10 did not think of themselves as fully fledged grown-ups until they reached the age of 27.
Lisa Daisy, 34, told the BBC: "Even after a career, two children and being together with my partner for 10 years, it still took being married to make me feel grown up."
'Earlier than my peers'
But 42-year-old Carole Lutringer said she felt like an adult when she was very young.
"I had to cook from an early age, because my mother worked as a head teacher," she said.
"My mother came back home late, and my father was pretty useless in the kitchen.
"I had to be autonomous from really early on, and that's probably what made me feel grown up earlier than most of my peers."
Sana Khalid Khan also had adulthood thrust upon her.
She said it had been the death of her father that had made her grow up, at the age of 17.
"Being the eldest sibling and child, a lot of responsibility was poured on my shoulders," she wrote on the BBC Family and Education News Facebook page.
Join the conversation at the BBC Family and Education News Facebook page.
Some people came to the realisation of adulthood in more prosaic fashion.
Londoner Sam Nichols said a saucepan had made her realise how grown up she had become.
"I got excited about buying a new saucepan," she said.
"If that doesn't scream 'adulting', I don't know whatever will."
Of those 2,000 people asked did feel they were adults, the transition happened for half in their 20s, while a fifth said it happened in their 30s.
One in 20 respondents felt they had not grown up until their 40s.
Of those questioned, 55% said being an adult was dependent on major life events, for example having children, moving out of the parental home or getting married.
For others, such as Elaine Smith, in London, adulthood is merely a state of mind.
"I still don't feel grown up," she said.
"I can't believe I have full responsibilities of looking after a four-year-old. How did that happen?
"I'm 44 this year, so it may happen soon."
Commenting on Facebook, Sophie Caunter agreed.
"I'm 42," she said.
"I have an 11-year-old, a seven-month-old, a husband, and I still don't feel grown up."
Melinda Wilmot echoed her sentiments.
"I'm 58 and still waiting to grow up," she said.
"Growing up is overrated anyway," said Sophie.
By Rozina Sini, BBC's UGC and Social News Team