More twins are being born than ever. But defining their individuality is still a problem for many. Jack O'Sullivan finds out how artistic expression can help

THIRTEEN thousand miles might seem far enough to let you escape an identical twin. Yet, if you are an artist, even vast oceans may not release you from an obsession with your mirror image. So, although the sculptor Vanessa Pooley has been separated for years from her sister Veronica (living in Australia), their relationship dominates her work.

"I create female, stocky images, rather like Matisse's style," says Vanessa, now aged 39. The reason? "I always have my twin in my mind. She has been two stone lighter than me for a long time. I'm sure that she is happy to be thinner than me and I would like to be thinner. You have a sense of triumph when your twin is bigger than you because it means that you are thin. But I also think that it's wrong for me to be losing weight. Veronica is definitely too thin - she is only seven stone. So I think it is better to sculpt what I feel, rather than become neurotic. I want to say that these ample female forms are fine. But my sister is different. She doesn't externalise things like this. In a sense she sculpts her own body."

Vanessa Pooley is one of more than 90 artists who have contributed works to Twin Images II, an exhibition this week at The Fine Art Society in New Bond Street, London. The sale is in support of the Multiple Births Foundation, a medically based support organisation for families and professionals, celebrating its 10th anniversary.

Twin births are rising fast - up from 7,654 in 1985 to 9,726 in 1996 - partly because the increasing use of ovulation-inducing fertility drugs or IVF treatment often lead to multiple births. The fact that many couples are older when they conceive also makes them more likely to produce twins.

The closeness of twins exerts an endless fascination. We thrive on tales of uncanny coincidence, of one twin experiencing pain while her sister is in childbirth and the like. But sometimes their relationship can become suffocating and destructive.

"I have not enjoyed being a twin," says Vanessa. "You never have your own identity." Not surprisingly, the image she has exhibited is of a single woman, a statement of the individualism she has struggled to carve out for herself.

Amrit and Rabindra Singh, also identical sisters, have an equally obsessive history. But in their case, they behave, not as antipodean opposites, but as though they are a single artist. "We often work on the same piece together and you can't tell who did what," says Amrit, 32. "We have a habit of dressing the same, we always exhibit together and we make a point of not putting name labels underneath our work. We understand who did the works, but people often think there is only one of us.

"We are criticised for doing the same pieces. But we are expressing ourselves. We produce what we produce because of who we are. People cannot comprehend the closeness of twins. Similarity does not mean the same."

Other people's perceptions are often a big problem for twins. According to the Multiple Births Foundation, the most important thing is that each twin is an individual and should be treated as such, with his or her own identity. Giving twins similar names doesn't help, because people get confused. Girl twins in particular tend to be treated as the halves of one whole and are often dressed identically. In adolescence, problems can arise because children often struggle to establish their identity and as well as breaking away from their parents, they try to separate from each other.

The kinship and the separateness of twins became apparent to Colin Cafell in the few short years he shared with his twin boys. He lost his six-year- old identical sons, Nicholas and Daniel, when they were murdered, along with their mother and grandparents, in a notorious mass killing at their Essex home in 1985. Their uncle, Jeremy Bamber, was eventually convicted of the murder.

The loss of his sons led Mr Caffell to sculpt for the first time. "The twins brought me face to face with polarities," he recalls. "They were identical yet they had opposite characters. One was more feminine, one was more masculine, one more caring, the other more self-centred. I could see these opposites that I had played a part in creating. So when I lost my children I had to face these opposites inside myself, the twins inside me."

The piece he has contributed to the exhibition is called Ying Yang. It is of a double foetus, one child upside down with its head ready to be born, the other facing the opposite way around. "One is keen to enter the world, the other is saying, 'let's stay here'", says Caffell. "We all feel these opposites. When one accepts them, one begins to give birth to oneself. To me the image of the two babies almost ready to be born represents my sense of coming out of the bereavement journey. We can be good and bad, light and dark, that's what the Taoist principle of ying and yang expresses."

Kathy Ramsay Carr is another artist driven by bereavement to follow her calling. Her family has four generations of twins. But the dynamic in the artist's creative life has been the death of her own twin brother, James, who drowned when they were eight. "I didn't begin working as a painter until my thirties, when I had my own twins and I began to feel better about my own loss. I felt I could communicate with him through art. I feel his strength has come through my hand and gives me comfort."

Kathy Ramsay Carr's preoccupation with her brother's death is echoed repeatedly in a book also published this week. The Lone Twin, by Joan Woodward, (Free Association Books) explores the bereavement not only of twins who lost their womb partners later in life. There is also testimony of those who lost them at birth. Cynthia Whelan, for example, talks about feeling weighed down through her life with grief for her brother. She explains: "By being able to say how much I miss him, to express my anger at being left alone here in this world to fend for myself is liberating." Decades after the death, she acted out a burial for her twin. "I felt many emotions doing this - fear, sadness, grief," she recalls. "And yet there was a sense of completion, of a coming together for me which felt very profound."

n St Thomas' Hospital, London, has a Twin Hotline, seeking twins to help in research projects. The number is 0990 770099.