What do you do if your daughter asks to use the boys' loos, or your son wants to go shopping in a fairy dress? Lena Corner gets some gender guidance

When Natasha Kittelsen-Clifford's daughter Alice started in year one, overnight she turned into a "tomboy". She cut her hair short, played football and dressed like a boy. "I thought it was just a phase so I just went along with it," says Kittelsen-Clifford, "but my husband was really angry. He tried to force her to wear dresses, but that just made her rebel even more."

It wasn't long before Alice pretty much stopped playing with girls. "And when she went swimming she was really worried that the boys would find out that she was a girl, even though they knew she was a girl. She always wanted to use boys' toilets, too. It was quite extreme and very worrying."

The school suggested Kittelsen-Clifford should take her daughter to see a psychiatrist. "I took her along to the doctor and he said, 'Go away, She's absolutely fine'."

So Kittelsen-Clifford bided her time and after about five years, Alice grew out of it. "Overnight she switched back to being a girl. I asked her why and she said: 'I didn't want to do it any more. I didn't want to play football or climb trees, I wanted to be a girl again.' She is now the girliest girl. I think we are all so desperate our children should conform and be what we want them to be that we forget that actually they've got these incredible personalities. They do what they want to do."

It is a difficult question, though. What do you do if your eight-year-old son insists on turning up to birthday parties in a tutu? Or, if your 12-year-old girl relishes being continually mistaken for a boy? It's a subject that has been cropping up a lot recently. Angelina Jolie's daughter Shiloh Pitt-Jolie, who regularly steps out in fedoras, braces and button-up shirts, has been singled out by the media for her tomboy style. And earlier this year Canadian couple Kathy Witterick and David Stocker announced at the birth of their third child, Storm, they weren't going to disclose its sex to anyone apart from siblings. They wanted, they said, to allow Storm the freedom to choose exactly who he/she wanted to be and to challenge any expectations.

Oliver James, author of parenting book They F*** You Up, describes the whole endeavour as plain silly. "Obviously the parents know what sex Storm is, so it will nonetheless guide them because it's unconscious. I have a nine-year-old and a six-year-old of different genders and I struggle to overcome the experiences I had of being a boy with three sisters. My parents treated us differently and I really have to grapple with that to avoid doing the same."

James has various theories about why some children choose to be tomboys or tomgirls. The most obvious is that it's used to gain the attention of parents, but often it's not as simple as that. "It might also be that you're a girl surrounded by boys and the most effective way to cope is to try to be a boy too," he says. "It is also about identification," he says. "It could be you have quite a feminine father and a masculine mother and you are simply trying to identify with your mother or vice versa."

Another person trying to make sense of it all is French director Céline Sciamma, who has just made a film called Tomboy, about a 10-year-girl who convinces everyone she is a boy. It's been a surprise box office hit in France since opening in April. It has just been selected to show in primary and secondary schools across France as an education tool to encourage children to open up about issues of gender.

Sciamma herself was a tomboy and says she used to find being mistaken for a boy as hugely liberating. "I thought as a boy there was stuff that I could do that I wouldn't dare as a girl," says Sciamma. "Childhood is often referred to as the age of innocence but I think it's full of sensuality and ambiguous emotions. I wanted to portray that." It was important to her to make a film about gender from a female perspective. "Often when we talk about gender or transgender issues it's in relation to boys. We had the film Boys Don't Cry [about a transgender teen] but this story, with a gender-confused girl as the central character, is one that hasn't been told much. I feel it talks about everyone's childhood to some extent."

American writer Cheryl Kilodavis also became increasingly troubled by her child's gender confusion. Her second son started showing interest in girly things before he was even two years old. "In 2007 he started to show interest in pinks and dresses. I initially tried to redirect him – putting trucks or cars in front of him, but he wasn't interested. He was so young, I didn't want to be too forceful." At Hallowe'en in 2009 she took him shopping for a costume. "Of course he wanted a princess outfit and I was having a very hard time with that. My elder son turned to me and said, 'why can't you just let him be happy?' and at that moment I realised I was the one who had the problem."

Kilodavis started writing a diary of her son's behaviour, which has been turned into a book entitled My Princess Boy, published by Simon and Schuster. "The reaction has been phenomenal," she says. "It was a very pleasant surprise to discover that I wasn't alone and there's a whole world of people going through the same kind of thing. My son started school last week with a pink princess backpack so it's still a process for me. It's not as simple as to say it's all OK, there is some discomfort. He is different. All you want to do is make sure your child is safe."

One of the techniques Kittelsen-Clifford used at the height of her daughter's tomboy phase was to try to educate her about strong female role models. "I felt part of the problem may have been that kids growing up these days don't see many women as really strong role models, all they see is strong, domineering men," she says. "So we made a real effort to talk to her about famous female warriors – Boadicea or Joan of Arc, and tell her that actually women can be really strong too. I think she found that very helpful. But it was hard. There is no rulebook."

OIiver James believes that if it is of concern, then you should seek help. "I would sit down in with a good development therapist and discuss the possible meaning that it might have for the child and take it from there.

"I'd simply want to help them be less confused. And on a practical level I would think it is going to create all sorts of trouble for them at school — so you're probably not doing them any favours by being wildly politically correct and saying, 'Oh great, lovely darling', because the boy who dresses as a girl is going to get the shit kicked out of him, and the girl who dresses as a boy isn't going to be responding too well to girls. If you've really got a need to have a boy who looks like a girl, is it really fair to foist that on your child? I wouldn't want to pathologise it but it is definitely something you should look at."

Tomboy is in cinemas now.

Tomboy tactics

* Ask yourself how you feel about your child's cross-gender behaviour, advises Rachel Andrew, a chartered clinical psychologist. You may be worried, upset or ashamed about it. Just recognising how you feel can help.

* Spend some time thinking about why you feel the way you do. Often we have certain ways we think our children should behave. These "shoulds" can often lead us to worry that there is something wrong or we haven't parented properly, when this is rarely the case.

* Don't make a big deal out of it. If you have to say something, ask your child about it in a calm, non-judgmental way. If you can't do that, just ignore it.

* Reassure yourself that there is nothing wrong with your child and that this behaviour is very common, particularly between the ages of five and 12.

* See it as a positive! Cross-gender behaviours often include the qualities of risk-taking, bravery and determination.

* See your child as a whole. Your child's gender-based behaviour is just one part of who they are.