Should you tell your daughter she's beautiful?

When I was 10 I asked my mum if I was pretty. "Yes of course," she said, without looking up. Then she looked up. "Well, not chocolate-box pretty," she added. The "chocolate box" phrase was new to me, but I could guess the meaning behind it. What she meant was: look, there's nothing wrong with you, your face is roughly symmetrical and you've got a lovely smile. But those looks aren't enough to make advertising campaigns, so if this has got anything to do with your obsession with gazing at the models in the Freemans catalogue and repeatedly asking me what "ecru" means, you'd better think of something more interesting to do with your life instead. So I did. She was right. I was annoyed for about 20 minutes and grateful for the rest of my life.

You'd think, then, that I would support the Liberal Democrat MP Jo Swinson, a junior equalities minister, who last week warned parents against telling their daughters that they are beautiful, urging them to praise girls for completing tasks well instead. Indeed, it would be a fairly nutty parent who wanted their child to be obsessed with their image, or turn into the sort of person who is late for school because, as in one of Swinson's anecdotes, it takes them two hours to do their hair. Yet I still shuddered when I heard her suggestion that beauty was not appropriate subject matter for your children. On the contrary – beauty is a beautiful thing to talk about.

I worry that we're all getting so very British about the body, so stand-offish and hands-offish, that we will lose the sensual connection to the form at all. And, weird as it might sound, that's a connection that matters to children too. Surely, in a world of body-image obsession, it's all the more important for children to know that they are the apple of a parent's eye? Telling a child, male or female, that they are a joy to look at, is one of the sweetest things a parent can do.

Giving any praise at all can have unexpected consequences, though. Carol Dweck, a Stanford professor, has been monitoring children's coping and resilience mechanisms for 40 years and says praise, not lack of it, can really interfere. In her long-term study, "Parent Praise", she observed the way parents encouraged their toddlers. For some, it was person-based, such as: "You are really smart". For others, it was about the process: "You must have tried really hard." She observed the same children at age seven and eight, and found the process kids much more willing to take risks, while the kids told that they were clever cared more about keeping up with that and less about actually learning.

"The parents who gave more process-praise had children who believed their intelligence and social qualities could be developed and they were more eager for challenges," Dr Dweck told The New York Times in 2011. Being repeatedly told you're clever can make you scared to look anything but. Does the same go for being told that you're beautiful?

Another study I read suggested that boys perform better in school sports than girls do because they are raised with rough-and-tumble play, whereas girls are encouraged to be more careful in their own space. Which is why I resolved to throw my toddler daughter in the air and charge around the park kicking a ball at her, as you more often see a dad doing with his son. When a bunch of friends with babies had a conversation worrying they were raising their kids to be girly or boyish, I thus felt a little superior that I had all that gender stuff nailed. Until the mother of a boy said how often she heard herself telling her son he was strong.

Strong – I racked my brains for a time I had told my little girl she was strong. Clever, yes. Cute, yes. Fat – I must admit, I had squidged her tummy and joked about that enough times too. But strong – no, I had never said the word. It has since become a standing joke in my family that we must now say it as often as possible. Oh look, she's put her socks on by herself. Oh look, she's opened my handbag and is hurling credit cards across the room. Oh look, she's ripping up a toilet roll and inserting it into a pair of wellies.... Quick, for God's sake, someone tell her she's strong.

She is strong, though – she likes nothing more than building enormous towers of Duplo and then bashing them down. So when somebody showed me a Lego advert from my own childhood, I didn't know whether to laugh or cry. In the ad, a girl of about five is holding up a complicated house she has built. This budding builder has long auburn plaits and is dressed all in blue, though you don't really notice that. What you notice is the immense pride on her face, and the words, typed across the page: "What it is is beautiful." The house is beautiful. Her joy is beautiful. By extension, she is beautiful too.

It's a brilliant advert – especially compared to Lego's current ones, which show lots of new pink stuff aimed at girls, with depressing tag lines such as: "Build a fairy tale world with My First Lego Princess featuring a horse, carriage, grooming station and pretty pink castle!" Or this mind-numbing one: "Get building in pretty pink style with a Lego brick bucket full of fun elements and bright bricks in perfect shades of pink." My brother and I used to pool our sets and build imaginary cities and space stations together for hours – imagine if we'd felt the need to separate my bits out, because they were pink.

Still, fear of a world overrun by pretty pink princesses shouldn't scare us off from telling both sons and daughters that they look good. Or encouraging them to make a bit of an effort and take pride in their appearance. Enjoy themselves. As Nora Ephron wrote: "Oh, how I regret not having worn a bikini for the entire year I was 26. If anyone young is reading this, go, right this minute, put on a bikini, and don't take it off until you're 34." I remember my huge shock, after a day of athletics at secondary school, when some boys from my class told me I had great legs. They were nice boys, saying a nice thing, and I had no idea. Had I been told the good news about my legs more often, I might have let them out in public more than once a year.

All of which reminds me of a schoolfriend who was also interested in fashion, as I was. Unlike me, she went on to be a model. She even made the cover of Just Seventeen. Her mum still tried not to let it become "a thing", saying that if that magazine was the best it was going to get for her, she'd better have something else up her sleeve. Natasha has since become a director of music videos. But she thinks her mum's approach was wrong. I asked her this week what she would have liked to have heard when she got that magazine cover.

"I'd like her to have said congratulations," she replied.

There is something about limiting praise – it can be dressed up as good intent; as making sure that young women strive to be the best person they can be. But sometimes holding back on a compliment is just holding back on a compliment. And – particularly when it happens between a mother and a daughter – it can sting. We have to ask ourselves why we are really doing that.