By NATASHA COURTENAY-SMITH

Last updated at 16:43 21 November 2007

With their dark hair, strong noses and refined chins, it is immediately apparent that women of the Clark family are related. Each is a feature that has been passed through the generations, and will no doubt appear in their children and children's children for years to come.

But there is one part of their bodies that does not appear to have been handed down the family line: their breasts.

The matriarch of the family, 69-year-old Yvonne Clark is a 36B, while her daughter Angela Stanton, 51, grew into a C-cup. And the pattern of increasing breast size continues into the next generation: Angela's daughter Tracey's breasts are a 32G.

"I got my first bra when I was 11 - I was a 32A and one of the first girls at school to need a bra," says Tracey, who lives in Buckinghamshire with her mother.

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"After that, I developed at an unbelievable rate. At 15, I wore a 32E. It seemed unusual considering my mother and grandmother had never been that big, and most of my school friends were still wearing B-cups. I'm now a 32G and have been this size since I was 20.

"I love having big breasts. When I get dressed up to go out in the evenings, I make the most of it. It makes for a great neckline and my friends associate me with my big chest. I wouldn't want to be known any other way."

Some might call Tracey lucky, but, in fact, she is part of a quantifiable scientific reality: British women's breasts are getting bigger with each generation.

The average bra size in the UK is now 36C, whereas just a decade ago it was 34B.

This week, it was announced that in response to demand, Marks & Spencer's is to stock J-cup bras for the first time. Previously, its lingerie department went up to G, but it will now offer GG, H, HH and J.

Earlier this year, Bravissimo, a bra company that specialises in larger sizes, introduced three different K-cup bras - in response to customer demand. At this rate, we'll all reach the next millennium with figures like Jordan's, except our breasts will be natural, not silicone.

"Since the first Bravissimo shop opened in 1999, we have seen a steady flow of women throughout the UK who need a K-cup bra," says Jacqui Geraghty, of Bravissimo. "There is nothing unusual in this bra size any more."

Looking at her family line, 67-year-old grandmother Barbara Haywood, a ballroom dancing instructor, is a little taken aback by the increasing size of breasts through each generation. Her 22-year-old granddaughter Miranda's 30G breasts swamp her own 36B bosom.

"In my day it was only old, stout ladies who had big bosoms - the sort who might lean over the garden fence and talk to the neighbours," says Barbara, who lives in Nottingham. "But today it's young women, such as my granddaughter Miranda, who seem to wear the biggest bra sizes.

"My friends and I still had the underdeveloped bodies of children when we were 18. I wore ankle socks and plimsolls until I left school at 15, and wore my first bra some time after that.

"Diet and lifestyle are so different these days. When I was growing up we ate a basic diet of meat, game and vegetables. Chocolates, sweets and puddings were a treat and we'd spend our time riding our bikes and playing outdoor games - not sitting in front of computers. I'm not surprised the young generation are bigger all over - I probably would have been if I'd consumed all that they do."

Contrast Barbara's experience with that of her daughter Denise, 42, who is a 34FF and her granddaughter Miranda, a bra-fitting consultant, who is a 30G and wore her first bra - a B-cup - at the age of 11.

"I really notice the difference when I look back at old photos of generations of our family,' says Miranda.

"The women of my gran and great-gran's generation had very slender figures with small busts and minuscule waists. That couldn't be further removed from the figure I've landed up with.

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"I love my big breasts now, but I hated them when I was at school. I dreaded sports lessons because my breasts would bounce around during netball and rounders and all the boys stared at them.

"Now, although my chest is often the first thing men notice about me, they soon realise I have a lot more to offer. I used to think about having a breast reduction because I felt selfconscious. Now, having big breasts makes me feel womanly."

So why do women today have bigger breasts?

Some experts say the boom in bust size may be explained by the popularity of cosmetic implants: 10,000 breast implants are carried out every year.

Significantly more women have breast enhancements than they do reductions: 2004 figures from a BUPA Hospital in Edinburgh show that of the 21-30 age group who had cosmetic surgery, 60 per cent opted for breast augmentation and only seven per cent wanted a breast reduction.

Other experts highlight the effect of hormones - breast tissue is extremely sensitive to these, with some women finding they need a bigger bra in the week leading up to a period. This is a major reason why the contraceptive pill - which also leads to fluid retention in the breast - has been linked to the increase in breast size.

"There is a tendency for the pill to stimulate breast growth," says Professor Pierre-Marc Cilles Bouloux, a consultant endocrinologist and physician at The London Clinic. "However, modern versions of the pill contain far less oestrogen than their older counterparts, so it is not fair to attribute this shift in its entirety to the pill."

The residual oestrogen that gets into the water supply from people on the pill is also thought by some to be a factor.

Other speculative theories include the suggestion that levels of artificial hormones in the foodchain could be affecting breast sizes, though there is no research to back this up. Foods from baked beans to almonds have also been touted as factors in increasing breast size, but this is speculative.

In fact, it seems that the most significant and likely explanation for our growing bust size is the simplest - bigger breasts is a result of weight gain all round. Since the 1950s, the average female waist has risen from 27.5in to 34in. So, is it any wonder that breasts are getting bigger too?

"It's well known that as a population, we've all been getting bigger," says Dr Joanna Scurr, a principal lecturer in biomechanics at the University of Portsmouth. "The larger we become overall, then the larger women's breasts will become. There is not any evolutionary reason breasts are getting bigger: it's simply a consequence of us all becoming generally bigger.

"Breasts are increasing because women today have a higher proportion of fat in their breasts than they used to. The structure of the breast is divided into the functional glandular element - comprising the milk ducts and support tissues - and fat.

"The functional part of the breast changes size at certain points during a woman's life. It will get bigger when she's pregnant and breast-feeding - this is why women's breasts generally get bigger at this time, and smaller when they're going through the menopause. This is because the body no longer needs the breast for milk.

"But otherwise this functional part of the breast doesn't change. So the increased breast size is due to the increase in fat that women carry."

The Mail's nutritionist Jane Clarke agrees that weight gain in general is a major factor in the increase in women's bust size.

"We're eating more - and of the wrong sorts of food such as crisps and chocolate," says Jane. "All those calories end up on the hips, and breasts. Women are also drinking far too much alcohol, which is not only unhealthy but highly calorific."

Like Miranda, Jane-Louise Atherton, a 22-year-old fitness instructor, is also significantly better endowed than her mother and grandmother. "My breasts suddenly appeared out of nowhere as A-cups when I was 13 and didn't stop growing until they hit a FF at 18," says Jane-Louise, who lives with her parents in Macclesfield and works as a part-time model.

"I actually used to be called pancake at school before I wore a bra. I'm only a size eight, so I can't blame my large breasts on being overweight.

"But big breasts aren't all they are cracked up to be. It's true that men zoom in on them, but I can't wear fashionable backless tops or boob tubes because they don't offer any support.

"When you've got large breasts it's incredibly expensive to buy wellfitting bras because they cost at least £30 - and that's without the matching knickers. I look at the older generations in my family and I'm envious of their figures.

"My grandmother has an amazing figure for an 80-year-old. She's only a size ten and has tiny feet and slim ankles. She wears elegant heels and co-ordinates jewellery to wear with her clothes. Mum looks great, too, and has a very slim waist which accentuates her curves."

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Certainly, Jane-Louise's grandmother Betty Cox, 80, does not feel she has missed out by having a smaller, 34B breast.

"I was a skinny little thing when I was young and didn't need a bra until I was 14,' says Betty, a retired tap dancer who lives in Macclesfield. "I'm happy with my body and especially my breasts. They are a good size and in proportion to the rest of me. I love the fact that dancing has given me a lean figure, even in old age, as well as graceful posture.

"It's strange how bust sizes are getting bigger, although it's difficult to tell which breasts are natural and which are false. Women are taller, curvier and even their feet are bigger. I only take a size three-and-a-half shoe, whereas my granddaughter Jane-Louise is a five."

Jane-Louise's mother Linda, a 34DD, also envies Betty's silhouette. "I would love to have a figure like my mum's," says Linda, a sales assistant, who lives with her husband Keith, 56, and their other daughter Lauren, 22. 'I've always been a C or a D, but being smaller would make it easier to buy more fitted clothes.

"I admit I was a bit surprised when I took my girls to Marks & Spencer's to have bras fitted and they ended up being more buxom than either my mother or I. But that is just the way things seem to be going.

"I think it must be down to all this processed food and sugary sweets that young people eat today. I have lots of friends who look at their daughter's breasts and wonder where they have come from."

It is a sentiment with which Yvonne Clark, 69, agrees. She admits to being entirely flummoxed as to the

origin of her granddaughter Tracey's G-cup breasts.

"The funny thing is, I've been a 36B all my life," says Yvonne, who lives in Buckingham with her husband, William. "Young girls wore vests, not bras, when we were growing up and I didn't buy a bra until I was 15.

"But in my day, we didn't look at every single girl's weight, or bust size. Being healthy was the main thing and it still is. That said, I have definitely noticed that young girls today are lucky enough to have the sort of ample bosom that my generation could only have dreamed of."