Ever felt a bit immature? Well, don't worry. People don't become fully "adult" until they're in their 30s, according to experts. While, in the UK, we legally become adults at 18, research suggests people in their late teens are still going through significant changes in the brain. Professor Peter Jones, from Cambridge University, told the BBC back in 2019: "What we're really saying is that to have a definition of when you move from childhood to adulthood looks increasingly absurd. "It's a much more nuanced transition that takes place over three decades." He added: "I guess systems like the education system, the health system and the legal system make it convenient for themselves by having definitions." When you reach 18, you can vote, buy alcohol, get a mortgage and are also treated as an adult if you get in trouble with the police. Despite this, Professor Jones says he believes experienced criminal judges recognise the difference between a 19-year-old defendant and a "hardened criminal" in their late 30s. "I think the system is adapting to what's hiding in plain sight, that people don't like (the idea of) a caterpillar turning into a butterfly," he said. "There isn't a childhood and then an adulthood. People are on a pathway, they're on a trajectory." Meanwhile, in an interview with PBS, Dr Jay Giedd, chair of child psychiatry at Rady Children’s Hospital-San Diego, said that the development of the prefrontal cortex, the part of the brain responsible for social interactions, regulating emotions, controlling impulsive behaviour, and assessing risk, doesn’t stop at age 18. Instead, he said it takes almost 25 years. So give yourself a break unless you are in your 30s. And if you are? Grow up. Sign up to our free Indy100 weekly newsletter Have your say in our news democracy. Click the upvote icon at the top of the page to help raise this article through the indy100 rankings.