It is a truth that parents of every teenager will recognise. Adolescents are less likely to notice the smell of sweat, cigarette smoke and soap, according to a new study. However, youngsters – so often content to live in fetid bedrooms with overflowing washing baskets – have quite sensitive noses when it comes to picking up the scent of junk food and ketchup. Researchers from Aarhus University in Denmark tested dozens of common odours on 410 people aged under 50. While nearly every participant was able to detect the overpowering signature of things such as petrol, coffee and fish, a generational gap opened up on many others. The adults had developed a relatively cultured sense of smell for herbs and spices and basic foods such as bread and lemon. And they also outpointed the 172 participants aged between twelve and 18 on many less pleasant tasks. One in seven youngsters couldn’t recognise sweat and ten per cent failed to identify cigarette smoke while grown-ups scored 92 and 97 percent respectively. Adults also had the edge on detecting soap. However, children came into their own when asked to pick out coke, ketchup, biscuits, candyfloss, fruit gums, marshmallow and Mars Bars. The study – published in the journal Chemical Senses – provides a possible explanation for why teenagers are seemingly immune to the smell in their rooms. It claims that youngsters may need to become accustomed to odours over many years before they begin to register prominently. Lead author Alexander Fjaelstad – assistant lecturer at the university’s Flavour Institute – said, “Our findings in adolescents are in line with the hypothesis that children may lack odour-specific knowledge which accumulates throughout life. Though odours are potent triggers of autobiographical memories from as far back as the first decade of life – and in a way closely linked to memory – the ability to name odours is an acquired skill that takes years to master.” Justine Roberts, chief executive of the parenting website Mumsnet, claimed the findings were unlikely to resolve long-standing stand-offs between mother and fathers and their offspring. She said, “This seems like a deeply unfair distribution of talents. When it comes to untidy bedrooms, surely parents would benefit more from the superpower of being unable to smell. Meanwhile, teenagers could perhaps usefully develop the ability to ferret out ancient tortilla chips from under a pile of mildewed bedding.”