The photograph, now faded and creased, shows three happy, chubby faces staring out. Twin babies are snuggled up on a sofa beside a smiling girl with tumbling black curls.

The image is the treasured possession of Maddy Bown, the older child in the picture, and it’s one she keeps in her purse at all times. Maddy is now 17, while the twins — Alex and Ruth — are 12.

Looking back reminds them all of their carefree early childhood: rainy holidays in Wales, blustery dog walks, pretending to fly on the swings in the park. As idyllic as it may sound, though, the fact is that the people in this portrait are as far removed from a traditional family as you can get.

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This graphic explains the complicated biological and adoptive relationships that are present between Ellen Bown's (far right) family

One woman — Ellen Bown — gave birth to all three of the children in the picture. But only Maddy is her ‘official’ daughter.

When it comes to Alex and Ruth, Ellen acted as a surrogate for her own mother, Jenny. Ellen used her own eggs, fertilised with her stepfather Tony’s sperm. So, biologically, twins Alex and Ruth are teenager Maddy’s half-brother and half-sister. But legally — having been adopted by Ellen’s mother Jenny and stepfather Tony a week after their birth — they are now her aunt and uncle.

Which brings with it another mind-boggling twist. To the twins, Ellen Bown is both their biological mother and their legal half-sister. Meanwhile, Jenny and Tony are their biological grandparents but legal parents. To say it’s an unconventional and complicated set-up would be an understatement — but it certainly isn’t unique.

Just last month, the Mail broke the story of Anne-Marie Casson, a mother who brought a child into the world for her single, gay son, Kyle. Unlike Ellen in this instance, she did not use her own eggs, rather acting as a surrogate for a donor egg fertilised by Kyle’s sperm.

And in February, retail expert Mary Portas revealed that her brother, Lawrence, is the genetic father of her son, Horatio, two.

Horatio was conceived through IVF, using Lawrence’s sperm to fertilise an egg from Melanie Rickey, Portas’s wife of five years.

Such stories have — understandably — sparked debate. Some have labelled these very modern interpretations of the family unethical, and have questioned the robustness of our surrogacy and fertility laws. But Ellen Bown and her mother Jenny Dias insist there is nothing perturbing about their situation . . . well, apart from the perplexing issue of what on earth they all call each other.

Ellen (left) has given birth to three children - Maddy, Alex and Ruth - but only Maddy is her 'official' daughter, Alex (right) and Ruth (centre) were legally adopted by Ellen's mother Jenny, and stepfather, Tony

‘We have always tried to stick to the adoptive relationships,’ says Jenny, 65, a retired saleswoman and receptionist. ‘So the twins call me and Tony “Mummy” and “Daddy”, as you’d expect. It’s only different with Ellen.

‘We got around that by them calling her “Tummy Mummy”. So I’m Mummy, she’s Tummy Mummy. That worked while the twins were little — now they just call her “Ellen”. She is a second mum to them.’

Ellen, 46, a trainee midwife, nods. ‘We have been open with all of them from the beginning about where they came from. Maddy was five when the twins were born. She knew that I was growing something in my tummy for Granny and Grandad and that, when they were born, they were going to live with them.’

Alex — bubbly, polite and dressed in a smart blue suit and school shoes — chimes in, unprompted: ‘People ask me all the time at school, but it’s just labels. We’re a normal family.’

‘Normal’ may well be a stretch for some people, but it’s clear from a few minutes in the extended family’s company that they are a closely knit, happy unit.

Ellen (seated centre) says the family have been open with all three of the children right from the beginning

Twelve-year-old Ruth, a tiny, pretty thing with huge brown eyes, sits on her half-sister/aunt Maddy’s knee, showering her with kisses and posing for selfies. Alex kicks his chair leg and is gently told off by adoptive dad Tony. Ellen appears and Ruth loiters by her birth mother’s side, then bounds over towards her adoptive mum Jenny to cling to her arm.

There are striking similarities between the twins and their biological parents, Ellen and Tony. Both have Ellen’s openness and warm smile, Tony’s mischievous eyes and striking dark skin (he was born in Kenya and grew up in India before moving to Britain).

Maddy’s father — who is no longer in Ellen’s life — was Jamaican, so the trio’s physical appearance gives the impression that they are full siblings.

I was at the right time of my life. It seemed like the most natural thing to do. Ellen Bown

Today, they all live just ten minutes from each other in Uxbridge, West London — Ellen and Maddy in one house and Jenny, Tony and the twins in another.

So, exactly how did this unusual arrangement come about?

When Tony, now 54, and Jenny met in 1992 through their work at British Telecom, they never dreamt they would have children together. Though he was at the time just 31, Jenny was 42, with a grown-up son and daughter by her first husband, and had undergone a hysterectomy for health reasons five years earlier.

Dating turned into a serious relationship and, in 1999, Jenny and Tony decided to get married.

It was Ellen who first raised the subject of children — in fact, over the wedding breakfast, at a local Indian restaurant. ‘I said, “What are you going to do about children? You’re married now — all you need is a couple of kids”,’ says Ellen.

It planted the seed for Jenny and Tony and, when the subject came up in conversation again, Jenny told her daughter Ellen that they were considering surrogacy.

‘I said, “Don’t do that. Don’t ask a stranger,”’ says Ellen. ‘If they were going to have a baby, they might as well let me have one for them.

Ellen (right) is seen here with Ruth (left), Maddy (centre left) and Alex (centre right). Ellen is the biological mother to all three of the children but is only 'officially' Maddy's mother

‘I was at the right time of my life. It seemed like the most natural thing to do.’

At this stage, Jenny thought she might be able to harvest her own eggs for the surrogacy, despite her hysterectomy. But fertility tests revealed they weren’t usable — so the couple broached the subject with Ellen of using Ellen’s own eggs.

‘If it couldn’t be mine, Ellen’s eggs were the next best thing,’ says Jenny. ‘I wouldn’t have felt comfortable adopting someone else’s baby where I didn’t know the family history. At least I would be biologically related to them this way as, genetically, they would be my grandchildren.’

Ellen, at the time 32 and a single mother, said yes without hesitation. ‘I was shocked she was so blasé about it,’ says Jenny, ‘but she is very strong and selfless. She brought her daughter up alone so beautifully.’

Jenny got in touch with the London Gynaecology And Fertility Centre in Harley Street in October 2000, and they began a series of mental and physical assessments to have the surrogacy approved.

Ellen (back left) was 32 and a single mother herself when she offered to carry a baby for her mother, Jenny (back right) and stepfather, Tony

Their first efforts were unsuccessful. The clinic was happy to proceed with the surrogacy — but only with donor eggs, not Ellen’s. There were concerns about Maddy’s psychological welfare, as well as Ellen’s ability to part with the baby after birth.

‘We were horribly disappointed,’ says Jenny. ‘The possibility of becoming parents occupied mine and Tony’s every waking moment. But we weren’t going to be put off.’

The three appealed the decision, and, after another round of psychological tests, were granted permission to try intrauterine insertion (IUI), where the sperm is inserted directly into the uterus, in February 2001.

We see each other all the time, we’re incredibly close. Ellen Bown

Jenny took a redundancy package from her sales job at BT, using her severance pay and savings to pay for the treatment.

Two rounds of IUI failed, so they agreed to try in-vitro fertilisation (IVF). Thirteen of Ellen’s eggs were collected, eight of which were fertilised. Two of the healthiest, most viable embryos were implanted. In total, it cost Jenny and Tony £9,200.

The process — using Tony’s sperm to fertilise his stepdaughter’s eggs — might give some cause to shudder, but Ellen insists she was never put off by the reality of what she was doing. ‘Before we started, I said it had to be done in a clinic,’ says Ellen. ‘I didn’t want any DIY stuff with turkey basters — that would be too intimate. But it wasn’t gross. It was in a petri dish — it didn’t mean anything at that stage.’

Ellen found out she was pregnant that December. ‘We did a test,’ she says, using ‘we’ as naturally as if she were referring to herself and a partner — when, really, she means her, her mother and her stepfather.

Jenny interrupts: ‘No, we didn’t. You were having pains and we went to the hospital because we were worried it might be an ectopic pregnancy.

While Ellen (pictured) was pregnant with the twins, her mother Jenny, and stepfather Tony took care of her daughter Maddy, did her grocery shopping and helped around the house

‘They did a scan and we could see these two little dots. One baby would have been brilliant — but twins! It was incredible.’

Over the following nine months, Jenny accompanied Ellen to all her hospital appointments, with Tony joining them whenever he could get time off work, elated by the prospect of finally becoming a father.

Tony and Jenny looked after Maddy for Ellen, did her grocery shopping and helped with the housework.

Friends and family were understanding as they knew how much having children meant to Jenny and Tony — and how willing Ellen was to help.

‘We’ve never had any really negative reactions,’ says Tony. ‘There may have been some comments on Facebook where people have called us weirdos, or asked what the hell we were doing, but most are very understanding.’ Ellen went into hospital for a planned birth in early May 2002, with Jenny and Tony by her side in the delivery room, anxiously waiting for their children to arrive.

Ruth came first, followed 40 minutes later by Alex, who had to be induced using a ventouse suction cap, as he was turned the wrong way round in the womb.

Ruth was born first and twin brother Alex arrived 40 minutes later, Ellen (right) is seen here at the twins' christening with her brother, Derek (left) and daughter, Maddy (front centre)

‘The birth was so calm and relaxed,’ says Jenny. ‘Ellen’s birthing plan was that she wouldn’t hold the babies, so the paediatrician handed them straight to me, then I took them over and showed them to Ellen.

‘It was surreal. Suddenly, they were there. It was really happening.’

Maddy came to visit her mother soon after, and the room filled with squeals of laughter as she laid eyes on the newborns. That night, Jenny stayed with Ellen at the hospital. It was then, she admits, that she felt the real emotional impact of what they were doing.

I kept asking and asking and then she just explained it. It didn’t ever matter. Maddy’s always been our sister. She just lives down the road. Ruth Dias

‘Poor Ellen was quite weak from losing a lot of blood,’ says Jenny, her voice trembling slightly. ‘It just didn’t seem fair. She wasn’t keeping these babies, yet they were in the same room as her. She could smell them, see them and hear them. It did get to me, because she is my baby, too.’ The next night, Jenny and the twins were moved upstairs. ‘That was lovely — just me and the babies together,’ says Jenny. ‘But I was worried about how Ellen was feeling.’

Yet Ellen says she had no idea her mother was so concerned. Of the birth, she says: ‘It was quite an experience. But I made sure I didn’t get attached during my pregnancy. I didn’t talk to my bump — Mum and Tony did that.

‘And in the delivery room, I never wavered. I just felt love.’

The adoption process was finalised the same week, and Ruth and Alex went home with Jenny and Tony.

Ellen was producing breastmilk so, not wanting to waste it, she sent it over, ready-bottled, to her mum.

‘That was perfect,’ says Jenny. ‘We fell into things naturally. I’d done it before, of course, and Tony was a wonderful father from the start.’

Today, Ellen and Maddy (pictured) live just ten minutes away from Jenny, Tony and the twins in Uxbridge, West London and the family see eachother regularly

Tony beams: ‘I could have coped with anything. The fact I was a father — all because of Ellen’s kindness — was more than I could bear.’

From then on, Maddy, Ruth and Alex grew up together, spending evenings round at each other’s houses and summers in each other’s gardens. They had never known anything other than their family set-up — and wouldn’t have changed it for the world.

‘I always wanted a brother or sister and I adore them,’ says Maddy, with a calm, confident manner. ‘There was nothing weird about it.’

Ruth chips in: ‘I started off by asking Mum [Jenny] how it worked and she told me it was too complicated because I was so young.

‘I kept asking and asking and then she just explained it. It didn’t ever matter. Maddy’s always been our sister. She just lives down the road.’

Maddy (centre) says she has always wanted a brother or sister and adores both Ruth (left) and Alex (right)

Discipline and decisions throughout the twins’ childhood — from what school to send them to, to how long to confiscate their Xbox for — have always been a shared endeavour. As have holidays.

On a recent break to Cape Verde, the twins stayed in a separate apartment with Ellen and Maddy to give Jenny and Tony a break.

Now in her mid-60s with two pre-teenage children, some might criticise Jenny’s decision to have babies at such an age — especially after she had already experienced motherhood.

But she refuses to be cowed. ‘It is hard work and I don’t think older people should go into it lightly,’ says Jenny. ‘I get tired and health issues have started creeping in.

‘There are so many things I’d love to do with them that I just can’t — taking Ruth horseriding, for example. But I never feel old. I’m young at heart, and the twins keep me that way.’

The family maintain that they are incredibly close and to them any confusing relationship titles are just 'labels', Alex (second right) says they are just a 'normal family'

Strangers, quite naturally, assume Jenny is the twins’ grandmother but, she says, that doesn’t bother her. ‘I’ll be out with the kids and people will ask, “Oh, is Nana in charge today?” And I’ll say, “No, actually, it’s Mum”.’

So how does Ellen see her relationship with the twins? Is she like another mother? A sister, perhaps an aunt?

For the first time, she hesitates. ‘I don’t know. I really don’t. We see each other all the time, we’re incredibly close.’ She glances at Ruth and Alex, larking around with Tony’s iPhone, and grins the grin of a proud mother.

Ellen catches Jenny’s eye — she’s wearing exactly the same expression. Their smiles widen.