We were sitting in a restaurant on the Mediterranean last summer enjoying a glass of chilled rosé when I put the question.

“How about another child?” I asked.

“I’d rather have another bottle of wine,” Rupert said.

“No, seriously,” I said. “What if it’s a boy?” “Only if it is a boy. But what are the chances of that?” A week of research on the internet had provided me with all the data. I explained that it was all down to diet and timing. Oh, and position.

“Position? As in the position of the moon?”

“No. Sexual position.”

I explained that while the missionary position is the preferred method for producing daughters, more exotic positions are likely to lead to the birth of a boy.

Suddenly I saw him calling for the waiter. Was he asking for more wine? “What are you up to?” I asked.

“Calling for the bill. There may be no time to waste.”

The next day I called my friend Annika (Brocklehurst) in England. While I was desperate for a son, she already has one and was keen on a daughter.

“I felt a daughter would balance the family well,” she says. “And having one of each would mean I was pretty much sorted.”

I suppose it sounds a bit frivolous of us to talk in these terms when some women can’t have babies at all. But I do think our desire to manipulate nature is defensible, particularly compared with the distressing revelation last week that scientists are discussing how to create babies from eggs “harvested” from embryos that have never been born.

What could we do to have our boy and girl? In England it is illegal to use preconception gender selection except on medical grounds. That is why people go to Spain or elsewhere for techniques such as “spinning”.

This works on the basis that the female chromosome, the X, is heavier than the male or Y. When spun the female sperm sinks and the male sperm floats. If you want a boy or a girl the appropriate sperm is then artificially inseminated. Even so, the chances of success are no higher than 75%.

In America, where this sort of sex selection has just been made legal, there is a new technique called MicroSort, in which the sperm is sorted according to size.

At the Laguna Hills clinic in California, they claim a 90% success rate for those seeking a girl baby, and a 75% success rate for those after a boy, although it is still at the testing stage and has yet to be approved by the US Food and Drug Administration.

How could Annika and I be sure to get what we wanted without resorting to science? We trawled the internet to find out and discovered the three main things we could do to tilt the balance in our favour.

The most important is timing. The suggestion is that while the boy sperms travel quicker, they don’t hang around as long as girl sperms. If I wanted a son I needed to have sex close to the time of ovulation. Obviously, for Annika, the reverse held true.

To work out the exact days we should be seducing our husbands, Annika and I logged onto conceptionstore.com. The website allowed us to input our details into a calendar for free. We each keyed in vital dates: the beginning of our last period; the length of our cycle. It then calculated the days we could get pregnant, when we were more likely to conceive a boy or a girl, and the days we were not fertile at all.

It told me that to conceive a boy I should abstain from sex early on in the cycle and really go for it on the so-called “peak” day, the day I actually ovulated, as well as 24 hours afterwards.

Conceiving a girl is said to be more difficult as the timing is tougher to get right. But in broad terms one should abstain from intercourse once ovulation starts. The peak day for a girl is three days before ovulation.

Second, diet. According to www.genderlabs.com, a non-profit website that promised we could “pre-select the gender of your baby naturally”, the first thing was to change our eating habits according to the gender we wanted.

For a boy I needed an alkaline environment and for a girl Annika had to create an acidic one. The diet for a boy is high in sodium and potassium, a girl is based on milk products.

The boy diet is altogether more appealing. I could eat and drink more or less everything I wanted except for milk products, seafood and wholemeal bread. In fact a coffee was positively recommended for both parties before intercourse as it might speed up the sperm.

In addition to the diet we could douche with bicarbonate of soda for a boy and vinegar for a girl prior to sexual intercourse. The smell of vinegar may turn some people on, but Annika and I decided that this was going too far.

Finally, we discovered that sexual position plays a vital role. And again I got the best of it by trying for a boy. Because boy sperms don’t live as long as girl ones, the aim then is to get them as close to the egg at the moment of ejaculation.

One method of helping this process along is for the female to reach orgasm first. According to one book I read, this advice was first written down in the book of Leviticus in the Bible.

The other tip the experts suggested was to go for maximum penetration. This is most effectively achieved from behind. For a girl baby you need the opposite, so it’s the good old missionary position. And there is no mention whatsoever of the female orgasm.

Armed with these three basic bits of knowledge, Annika and I went to work. “I spent two months eating yogurt, which I hate,” says Annika. My husband had to time his business trips to coincide with my peak boy-conceiving days.

Was there anything else we could do? As I live in France, I asked my French friends.

My husband had been right when he thought the position of the moon would have something to do with it. Here they plant, cut their hair and bottle their wine according to the lunar cycle.

According to Stephanie Bascou, who is pregnant with her first child, a lot of women in France follow the course of the moon when trying to get pregnant. “If you want a boy you’re supposed to have intercourse when the moon is ascending and if you want a girl when it’s waning,” she told me. “Or perhaps it is the other way round?” Annika and I ignored the moon cycles and amused ourselves instead by swapping ancient myths. Anaxagoras, a pre-Socratic philosopher of the 5th century BC, believed that semen from the right testicle produced sons, while semen from the left produced girls. Apparently this belief still persists in parts of the Balkans, where men who want a son will squeeze their right testicle on ejaculation. Neither of us could persuade our husbands to go this far.

Equally unhelpful was the suggestion from the Caraka Samhita, a manual written in the 8th century BC. This advocates that parents who want boys should “abstain from intercourse for a week, gaze every morning and evening upon a majestic white bull or stallion, while being entertained by pleasant tales, and feeding their eyes on men and women of gentle looks”. Annika observed that this would be very hard to arrange in Tunbridge Wells; just as well she wanted a girl.

So we sat back and waited and reassured ourselves that whatever happened, it was not our fault. Men, not women, influence the sex of the baby. Every egg produced by a woman carries a single X chromosome. If a female sperm fertilises the egg, the result is a girl. If a male sperm fertilises the egg, the result is a boy.

I told myself that it is not just spoilt westerners who try to influence the sex of their babies. In some parts of the developing world the issue is taken with deadly seriousness. In Bombay, a study of 3,000 abortions showed that all the foetuses were female except three.

I also realised that while for Annika and me choosing our babies’ sex was a matter of taste and it didn’t really matter if we got it wrong, for some people it was a matter of life and death. There are a number of genetic disorders that can be passed from mother to son such as Duchenne muscular dystrophy and haemophilia. In other cases there are diseases that can be passed only from mother to daughter, such as genetically linked breast cancer. Determining the gender of a baby, if possible, is therefore all-important.

I KNOW exactly where and when I got pregnant, and the position Rupert and I were in. I will spare you the details. Annika became pregnant at about the same time.

We were promptly faced with the choice of whether to find out the sex of our babies. In France, the attitude to knowing the sex is quite different to that in England. French people like to find out. At my first antenatal class we went round the group and everybody said whether they were having a boy or a girl.

I told them I did not want to know because not knowing the sex gets you through the pain of labour. The truth was that I didn’t want to find out it was a girl and watch my husband mope around for six months.

Because I am over 35 (just), my gynaecologist insisted that I have an amniocentesis. This checks whether the child has any chromosomal disorders like Down’s syndrome. I told him that while I wanted to know about Down’s, I did not want to know about the sex. He said it was a good job I’d mentioned it as they tell the mothers as a matter of course.

So I was more than a little surprised when three weeks later his secretary left a message on my answer machine, saying that the results of the test were fine, and that it was “un petit garçon”. I played it over and over again to be sure that I had heard correctly.

About the same time, Annika was in Harley Street having a scan. “I can see the sex of the baby,” said the doctor. “Do you want to know?”

“No,” said Annika. “Actually yes, well write it down and put it in an envelope.” The doctor did as she had asked. “I give you about three minutes from when you leave this room to open it,” she said as she handed it to Annika’s husband Tim. They walked outside and Tim asked if she wanted him to open it.

“Yes, no, yes, oh, go on then.” There was a rustling of paper behind her. “Well?” “Put it this way,” he said. “You won’t be buying anything blue.” So had we just got lucky, or had our hard work paid off?

Most people say it’s all nonsense. My best friend in France, Alexandra Mas, says her mother’s cousin tried all sorts of things but still ended up with five girls. “Personally I don’t believe any of it,” she says. “I can’t see myself ever doing anything to try to determine the sex of my children, I just don’t think it works.”

Most experts are sceptical that parents can influence the sex of the baby. According to my French gynaecologist: “It is a nonsense to think that you can affect the sex of your baby by witchcraft. It’s like flipping a coin. Every time you do it the odds are still the same.”

I have just read on another website that once you have had one boy, you are more likely to have another. Maybe I’ll tell my husband this bit of research next year. In the meantime, we’ve got the births to look forward to in a month’s time and then, if all goes well, the small matter of whether our son will be able to bat and bowl well enough to captain England. Dwayne Senior