It all started when my eldest son, Raymond, went from suddenly being a little boy to a teenager – turning into a surly Kevin from Harry Enfield's Kevin & Perry Go Large seemingly overnight. All sorts of things happen when your sweet children turn into rude and grumpy teenagers, but one of the major changes is not their attitude, but their smell. It just hit me one afternoon when Raymond, then 12, and I were chatting in the kitchen and I was suddenly hit by a distinctive waft of male body odour. He was the only other person there with me at the time, so I knew it had to be him. How do you tell someone you love dearly that they pong a bit and need to start using deodorant? What words do you use to soften the personal blow? It's the equivalent of telling people that their breath smells. As British tennis player Harriet Dart showed this week when she was caught asking the umpire to tell her French opponent Lois Boisson to put on deodorant, it's a difficult and sensitive conversation that risks shaming others. During a changeover in the second set at the Rouen Open, Dart told the official: 'Can you ask her to put on deodorant? She smells really bad.' Unfortunately, her comments were picked up by the court-side microphones. Cue much embarrassment for both players. Dart later apologised on her Instagram: 'That's not how I want to carry myself, and I take full responsibility. I have a lot of respect for Lois and how she competed today. I'll learn from this and move forward.' To which Boisson cannily replied with a shot of herself with some Dove deodorant and several laughing emojis. But it really shouldn't be such a thorny topic. It should be absolutely simple to say to someone: 'I'm telling you this to help you, but I think you might need to invest in some deodorant.' Yet we are so bad as a society at doing something which inevitably helps the person you are calling smelly. At first, I did tiptoe around the issue with my son. I would go into the kitchen and very dramatically sniff under my own armpits, asing my four children: 'Oh, do you think I smell?' Before anyone could answer, I would bring my deodorant down and make a show of liberally spraying it around, looking encouragingly at the kids. This tactic didn't particularly work... I think they thought I'd gone mad. So I tried a second tactic of starting to do my children's laundry every day to stop the pong. When they asked me if that was a bit excessive, I'd reply diplomatically: 'Well, as you all play sport, it's better to wash everything as much as possible so that it doesn't smell.' It was almost impossible to say the bare fact: you need to use deodorant. I assumed that they were being taught at school on how our sweat glands change during puberty, not only becoming more active but beginning to secrete different chemicals into the sweat that has a stronger smelling odour. While we hope that someone else will tell them that they need to use deodorant – their friends or teachers, for instance – the truth is that no one does, so it ends up being the parent's job. But even if they did know all this, I'm not sure teenage boys care as much about their personal hygiene as teenage girls do. My daughter Ottoline, who is now 18, thinks everyone should use deodorant. She would never dream of leaving the house without slathering on some Wild – a natural refillable deodorant. She's been using it for quite a long time and it's not cheap (around £13 for a 40g case). Some people claim that the 'natural' deodorants aren't as effective as cheap, bog-standard antiperspirants (you can get a 50ml Nivea one for 50p from Boots) which block sweat glands. But she insists it lasts for hours, which means she can go out and not worry about having to reapply. Then again, Ottoline's been wearing deodorant and perfume from way before she was even an adolescent. I think it's partly because she was copying me, but I also think girls are marketed at in a completely different way. They're almost enrolled not to be 'smelly' by advertising from a very young age. She would ask me as a pre-pubescent if she smelled when all she was ever really scented with was laundry detergent. But it's different for boys. It might be something to do with marketing, but when they do eventually start using deodorant they don't go much further than Lynx Africa which, of course, smells disgusting. But it is the one thing I think boys will wear without feeling like they're being 'unmanly' because it's marketed more as a body spray – and it's better than the alternative. My second son, Leonard, who is now 22, was very sporty and played a lot of rugby – and although it took me a few years to really convert my male children to the joys of deodorant, he did manage to get into Lynx Africa very early on. Rather than believing (falsely) that taking care of his personal hygiene was something that only 'unmanly' boys did, he went in the totally opposite direction. He still has about three showers a day and spends his entire life laundering his clothes with a very upmarket, 'planet-friendly laundry shampoo' from Tallow + Ash. And then there's the question of whether I really should have interfered: is it a person's right to smell? If you are living with four young people and three of them smell like yesterday's old socks or worse, let me tell you, something has to be done about it. It's a far more difficult conversation to have with adults. When I was at university I had a male friend who refused to use deodorant and didn't wash his clothes very much, too. I was seated next to him in an exam and I actually had to ask to move. If I had been braver I would have sat down with all my children and given them a long talk about the need to smell good – not just for themselves but others around them. But it's not easy to do, especially as a mother of male children. In the end I found Christmas was a perfect time to tell Raymond, and I bought him some Lynx as a present when he was 13 years old. When it was running out, I'd say sweetly: 'Shall I replace that for you?' It seemed to do the trick... and he, thankfully, seems to have stopped using the Lynx.