Since the introduction of IVF in 1978, the number of multiple births has almost doubled. Does this mean that twins and other multiples have lost their "specialness"?
By Caroline Briggs
Twins have been revered and feared throughout history.
Every culture has its twin myths. Voodoo practitioners in Haiti believe twins have magical ability and share a single soul. Some Native American tribes considered them unlucky.
And in the West twins, triplets and other multiples are a staple of daytime television on shows that are the modern-day take on the freak show.
This fascination with people who come in multiples - particularly identical twins - is because they make us question our sense of uniqueness, says Dr Nancy Segal, a psychology lecturer and twin expert at California State University, who herself is a non-identical twin.
MULTIPLE BIRTH STATISTICS
1975: 603,666 mothers giving birth, with 5,909 twins, 72 triplets, 4 quads, 2 sets of quins
'85: 653,142 mothers giving birth, 6,700 twins, 93 triplets, 7 quads, 2 sets of quins
'95: 642,404 mothers giving birth, with 8,749 twins, 282 triplets, 7 sets of quads
2005: 639,627 mothers giving birth, with 9,396 twins, 146 triplets, 1 set of quads
Source: ONS, England and Wales
"We tend to expect individual difference in appearance and in behaviour, so when we see two people who look so much alike - and are so much alike - this really draws our interest."
Because what does being a twin do to someone? For storytellers, twins represent duality, with one good and one bitter and twisted at having to share. The evil twin is a literary staple, from Romulus, the demi-god who slew his twin brother Remus to secure power in ancient Rome, through to outrageous storylines in soap operas.
"You can take good or evil, or bad and good, you can talk about twins as complementary," says Dr Segal, whose book Indivisible By Two examines the twin relationship.
"But a lot of people have extended that to say there is a good twin and a bad twin in every twin relationship, and that is just pure myth."
Gap in the market
In recent years the number of multiple births has increased, due to the use of fertility treatments and mothers delaying childbirth until they are older.
Today, about one in every 67 pregnancies results in a multiple birth.
Buggy makers cater for multiples
And the High St has responded accordingly. Greeting card makers offer congratulations on the arrival of multiples. Prospective parents can take out insurance to help cover the cost of more than one baby arriving at once. And supermarket trolleys no longer have just a single child seat.
This is down to efforts to make life easier for multiple birth families, says Keith Reed, chief executive of the Twins and Multiple Births Association (Tamba). It was 1993 before supermarkets began producing trolleys with seating for at least two children.
"It was one of our first and most successful campaigns because it made such a difference. You could go out and take your children shopping and just lead a normal life."
But twins and other multiples are still unusual enough to give complete strangers licence to ask the most personal of questions, he says.
"Twins are not uncommon, and yet people still react somewhat strangely towards them. The reserved British population seems to think they have the right to ask people how they conceived if they have got twins, which is something you would never dream of asking anyone else who is pregnant."
Claire and Michael Hall, of Newcastle, are all too familiar with this since becoming parents to Robbie and Isla in May 2006.
"I felt really special when I told people I was having two, but you can tell people are trying to find out whether they were conceived through IVF or not, when it really should not matter.
Twins Isla and Robbie Hall were born thanks to IVF
"People are fascinated by them. Everywhere I go people look at them and says how gorgeous they are. Lots of people come up to me and say: 'I always wanted to have twins'."
Because however familiar we become with those who come in sibling sets, what's special is their strong bond.
When researching her latest book about the nature of twinship, Dr Segal met identical twins Gerry and Mark, who were brought up separately and reunited aged 31. The men - both firefighters - felt they were so alike there was no need to get acquainted.
"Identical twins seem to have that right from the moment they are born," she says. "People are always searching for closeness and camaraderie and complete understanding. Tests show identical twins probably do have the closest social relationships of anyone."
Below is a selection of your comments.
I'm an identical twin and even now at the age of 23 people react strangely - either by asking ridiculous questions or staring in the street. Sometimes I think that people have never seen twins before!
I'm due to undergo IVF/ICSI next year and I will be asking for single egg transfer to avoid the medical problems associated with multiple pregnancies, a lot of people I know say they would love to carry twins - I can imagine the anxieties expectant mums and dads have carrying just the one let alone the larger risks with carrying more! All babies are special, not just twins and if my treatment works and someone asks me 'how I conceived' Il tell them in the test tube of love!
My younger brothers are twins (non-identical) and they quite often seem to be thinking the same thing, or will say a really strange thing absolutely simultaneously. One episode that sticks in my mind is a few years ago in a clothes shop when my dad was trying on a rather outlandish sweater and he asked us what we thought about it. At EXACTLY the same time, with the EXACT same intonation and pauses between their words, my brothers replied in unison: "It's a bit...jazzy!"
Hardly the stuff of legend but it was very amusing.
As far as I am concerned multiple births of two or more children as a result of IVF cannot in any way be compared with identical twins, triplets etc. These children are still special as they are a result of one egg splitting and grow up looking identical. Multiple birth children merely look like brothers and sisters.
Jan, Croydon UK
I am an identical twin and in my experience people treat twins as two halves of a whole rather than separate individuals. My twin and I have had to fight harder to be seen as independent individuals - which explains why we have chosen completely different careers.
Leigh, Belfast, N. Ireland
I have a twin brother and produced twins (non-identical) myself thirty years ago. There is nothing special about twins just alot of very hard work.
My mother was one of three identical girls born in the 1940s in the Midlands. She tells me that her mother grew so large late in pregnancy that people would stop her in the street to tell her she would never survive labour. Nice. Understandably she stopped leaving the house. Mother and daughters all survived and family photos certainly look very strange compared to other peoples.
Erica Nolan, Mountain View California
It may sound trite but I firmly believe all children are special and a wonderful gift we should treasure. I am a mum of three boys, non-identical twins and a singleton. I love all three of my lads and am thankful for each of them; their similarities and their individuality.
Katherine Gee, Christchurch, New Zealand
I have boy/girl twins who are 4. I also have 2 older daughters [not twins] so I can do a small comparison. I think there is something really special about twins [even those from IVF such as mine]; perhaps because they always have a playmate and never suffer from birth-order issues, have always had to share toys, they really do seem to be socially advanced - and I think there is medical research that shows this in general. That's an important reason not to limit IVF implantation to one embryo!
Steve, Stonington, Connecticut