The Secret Life Of Twins (2009) s01e01 Episode Script

Part 1 of 2

We've been known to kind of start singing a tune in pitch at the same time.
The same song.
Sometimes we think we're not the same, seeing all these other twins.
They're like replicas! Identical twins are nature's very own clones.
This makes them perfect case studies, helping scientists understand what makes us all who we are.
In the next two programmes we travel the world to show how studying both the similarities and the differences between identical twins is helping to reveal what makes us all tick.
No-one has ever asked me if I'm gay because my brother is.
Chris and Xand are identical twin doctors.
We'll follow their very personal mission to find out if they're destined to be alike forever.
As an individual, can I redeem myself a bit? Do you and I behave differently? And the answer is yes, we do.
I think the answer to that is no, we don't.
We'll find out if being raised apart has made twins Mia and Alexandra any less identical.
And five years after they were separated, we join them to share a very special moment in their lives.
We have plans to meet each other and now it's really going to happen.
She might not understand me.
Here they are.
We'll discover how scientists are learning from identical twins like Brittany and Stephanie.
Their very different appearances result from shared genetic traits which are helping to explain serious mental illness.
I was going to die if I kept going the way I was going, but that was never my I never wanted to die.
New discoveries helped by the study of twins are revolutionising the way we see the world.
Perhaps we can finally make sense of one of the oldest debates in science, are we born or are we made the way we are? Have you ever been unfaithful? CROWD: O-o-o-o-oh! It's uncanny how similar these things are.
My husband said, "It's like my wife in stereo!" Hands on your head on your shoulders.
Up, up, down step.
Up, up, down step.
In tonight's programme, we're going to explore how the study of similarities between twins is transforming the way we all think about ourselves.
Our tastes are similar, food, clothes, men.
We're both creative so, em, we like the same sort of things.
I think it's amazing that we're seeing loads of twins because I think other twins are weird, and it's like, I know it sounds strange, but you see other twins and think "Oh, my God!" Identical twins have always been a source of fascination, they cause a stir wherever they go because their likeness is uncanny.
Non-identical twins are just like ordinary brothers and sisters.
They come from separate eggs fertilised by separate sperms and on average share only 50% of their genes.
Identical twins, on the other hand, start life in an almost magical way.
When an embryo destined to be one person suddenly splits into two for no apparent reason.
They share 100% of their DNA, effectively making them clones of each other.
Identical twins make up less than 0.
5% of the world's population.
That's pretty rare, but nothing compared to this.
What you're about to witness is so unlikely, it's impossible to calculate.
OK, here comes munchkin number one.
BABY SQUEALS There we go.
Liz Thompson is giving birth to identical triplets.
Sweetheart, there we go.
Number two.
Here comes number three.
That in itself is so rare even medical textbooks don't list the chances of it happening, but what's even more extraordinary is that mum, Liz, is herself an identical triplet.
When I heard Liz was having triplets I thought they were joking.
I got really offended when Lizzie was pregnant and they'd assume I was Lizzie.
I was like, "Do I look pregnant to you?" There's no scientific evidence that identical twins and triplets run in families, but if they are just a coincidence, how do you explain this? The tiny settlement of Linha Sao Pedro in the South of Brazil is inhabited by an extraordinary number of human clones.
In a population of 375, there are 38 pairs of twins in an area just a mile and a half square.
That's 25 times the global average.
Geneticists have been trying and failing to explain this for decades.
It is a mystery that underlines why all identical twins are considered medical miracles, and why studying them is a privilege that benefits us all.
The physical similarities between twins can give us remarkable insight into how our bodies work.
Hi.
Meet Joy and Jane.
Hi.
Dr David Teplica studies how much of what happens to us physically is programmed before we are born.
BOTH:We were deemed the most identical set of twins in the state of Illinois.
I'm fascinated with how twins provide this incredible opportunity to get at some very important questions about basic human anatomy for all of us that have not yet been answered.
Your infra-orbital rim is 52.
5 inches from the floor.
Dr Teplica has been analysing identical twins for 20 years.
Can you put your chin down a bit? He uses medical photography, skin examination and digital analysis to compare their anatomy.
It's uncanny how similar these things are.
Ear creases, a little crease in front of the tragus of the ear in both.
A seborrhoeic keratosis at the root of the helix, the same shape and location.
It's a bit shocking to imagine that 20 or 30 features on one side of the face can be almost 100% in alignment with the twin.
Dr Teplica has also catalogued similarities between twins occurring as they age.
I've seen photographs of Donald and Lewis when they were younger and they didn't have these age spots and pigment changes in their childhood photographs.
So you might say, well, the environment made them develop these things, but if they show up in the same place, you know, and this shows up almost exactly in the same place, and we know that this is a change that happens only as one ages, it's illogical to think that the sun only shone on that one spot.
It can't happen.
This is so far beyond what any of us ever imagined could be true about the predetermination of anatomy that to me it says that we don't have any control over this.
That one egg and one sperm can determine which hair grows grey on your left eyebrow or your right eyebrow at age 83 is genetically predetermined 84 years earlier, is pretty amazing.
If Teplica's theory is that genes determine every detail of our anatomy right from conception, then what role might they play in shaping the way we think, the way we behave or even the choices we make in life? That's exactly what St Thomas' twins study is trying to explore.
All the twins at the party today have given their time, their bodies and their minds to researchers over many years, and today is their big chance to get together.
This is quite peculiar, isn't it? Chris and Xand Van Tulleken are identical twin doctors.
They've come to the party to join hundreds of pairs of other twins for the very first time.
That's what's funny, isn't it, is that all the twins are looking at all the other twins as if they're a bunch of complete freaks! The twin doctors are particularly interested in whether it's mainly nature or nurture that makes them the way they are.
Chris and I are similar in that we enjoy the same things, we both have a lot of the same friends.
We both did medical degrees, we did exactly the same A Levels, we got more or less the same grades.
We drink similar amounts of alcohol, we work similarly hard.
We both do things at the last minute.
I suppose the best example of twin confusion was at a party where I kissed a girl and some weeks later I was bragging to Xand about this and he looked a bit alarmed and went, "Wait a minute, I kissed her at the same party, what are you talking about?" So we phoned her up and said, you know, "Did you have any idea you kissed both of us?" And she went, "Oh, my god, no, no, I thought it was you twice!" And, er, yeah, it was me first.
We're not competitive, but But I was relieved about that! While they undeniably have a lot in common, there is one subject where Xand's opinion is very different from his brother's.
You're not just limited by your genes, your genes aren't an iron cage which constrain all your choices.
I think that you want that to be true cos you find it hard to go through life looking at this other person who looks the same as you, who's a little bit out of shape, who's going a little bit bald, who doesn't work quite as hard as he should, and it pains you cos you know, actually, those things are true about yourself.
How dare you? But it is, that's what you That's my experience of it.
You're wrong to insist that I'm basically constrained to being the person I am.
I think I am different to you, I think I do have some free choice, there are personality differences which are significant to me.
No, there aren't.
Like what?You're a bit more pushy than me, you're a bit more confrontational than me, you're more kind of motivated.
I have a sense you're the more motivated, pushy, neurotic twin.
Remember when we were ten and I came bottom of the class in every single exam, and everyone said, "Why don't you work a bit harder like your brother, you'll do better?" But I hadn't done better.
Don't you remember? You were last in every exam and I was second last in every exam.
So, you know, you can say, "Chris did better in the exams.
" Yes, on average I did, like, 1% better and didn't come quite bottom cos you were occupying that space.
Having grown up together makes it difficult for Chris and Xand to work out whether they are similar because of their genes or their shared experiences.
It would be easier to check if they'd had very different lives.
Thankfully, that's unlikely for most twins, but it is not unheard of.
China, 2004.
Two excited families arrive to pick up their newly-adopted adorable little girls.
There she is, your new mummy, she's going to go get her.
It's the biggest day of their lives.
BABIES CRY What's wrong? Are you OK? It's Daddy.
We're here now, we're gonna take care of you, yeah, we're gonna take care of you for the rest of your life.
Never gonna leave you.
'It's, of course, different than the birth process but I felt like, oh, my gosh, I had my child, 'and I knew I loved her right away.
' It was a dream come true, and, you know, it was just something that that I had wanted for so long and finally it was happening.
And she was just the most beautiful little girl.
'The next day we had to go back to the Civil Affairs Office to finish up paperwork,' and there was a group from Norway that was there finishing up their paperwork.
So when we got there I was holding Mia and I was walking around, and we see the other little girl that looks just like Mia and we just can't believe it, we can't believe that these two girls could look so much alike and not be sisters or twins or something.
Angela came to me and she said, "Oh, they must be twins, look how they look so alike.
" And we asked the Chinese lady, but she said no.
I don't think that we believed her, not me and not Angela.
When they got back home, both families ordered DNA tests which left them in no doubt that Mia and Alexandra were identical twins.
Ready, ready to stand up? 'People have asked us 'that maybe one family should have adopted both girls.
' I thought about that later and of course I think either of the families would have taken both girls, had we known.
But that thought never entered my mind that either family should take both girls, because those are Mia's my daughter, Alexandra is the Hauglums' daughter.
Mia and Alexandra are now six years old.
Their lives couldn't be more different.
THEY SING IN NORWEGIAN Alexandra lives in Fresvik, a tiny village in the Norwegian fjords, with her adoptive parents, Wenche and Sigmund Hauglum.
Do you want to try a cheeseburger? No.
Mia lives with her adoptive parents, Angela and Andy Hansen, on the other side of the world in Sacramento, one of the largest cities in California.
Apple juice! 'We both work full time so we have a very different schedule.
' A typical weekday morning I get her up about 6.
15, she has her breakfast, she gets ready for school, gets dressed, gets her hair done.
Naturally they have very different upbringings.
Mia already knows how to read, write and do arithmetic.
Mia?6,552.
Alexandra, on the other hand, won't start school till next year.
We get up in the morning and have breakfast together and after that she's free to do what she wants to do.
"Batter up!" called the pitcher.
The pitcher threw the ball.
Although the girls don't remember each other, Mia and Alexandra's parents vowed they would reunite the girls when the time was right.
We have plans to meet each other and now it's really going to happen.
But will they get on, or will their separate upbringings have made them so different they can hardly relate to each other? Does she know how to read? But she might not understand me.
Cos I cannot speak, um what's her language called? Norwegian.
I can't.
I don't even know "hello".
Alexandra, her parents, and her sisters, Michelle and Marlene, have arrived in Sacramento after a 30-hour journey from Norway.
This morning she was very excited and yesterday too she couldn't sleep, because she was thinking about Mia and see her.
Are you very excited?Yes! Super excited?Yes! Super-duper excited?Yes! Are you going to give her a big hug? Yes, like this.
Ooh.
Ooh.
Oh, my goodness.
She's got to come soon.
Can't wait too much longer.
Oh!There they are.
OK, wait, Mia.
Yes! Careful, Mia.
Yes! Can you open the door? Hello.
How about a hug? How about a hug, Mia? Can you give her a hug?Mmm Come here.
Hello.
Hello.
Hi.
Hi.
How are you? (Fine.
) Fine.
Erfine.
Good.
Why don't you take her hand and bring her inside? THEY LAUGH That didn't take long!No.
Despite the language barrier, Mia and Alexandra's bond is instantaneous.
SHE SQUEALS Don't worry.
Whoa! So Alexandra loves the water? Yes.
So does Mia, it's her favourite thing.
I'm going over there.
THEY LAUGH AND SCREAM I was kind of worried that they might not be able to communicate, but they seem to have figured it out.
And it's just It just is really amazing looking at Alexandra's expressions, it's like looking at Mia.
Yes, it's the same, yes, it's the same.
That look right there, that was Mia.
As we witness this extraordinary moment in the little girls' lives, a week of intense emotion has only just begun.
Can you both roll your tongue upwards? Back at St Thomas's twins' party, they're running a series of fun experiments, which promise to inform exciting new areas of science.
Here, researchers are looking at whether genes influence our behaviour and even the decisions we make.
Have you ever been unfaithful? CROWD: O-o-o-o-oh! Ladies! Naughty, naughty.
Professors James Fowler and Tim Spector have split the twins.
Identicals on the left, non-identicals on the right.
A blue card means the twins share the same opinion, a yellow one means they don't.
The way the classic twins' day works is we compare identical twins who share 100% of their genes to fraternal twins, who share about 50% of their genes on average, and if those twins come from similar environments, then what that suggests is that if the identical twins are more similar than the fraternal twins, then the genes are playing a role in whatever it is.
Are you within ten kilos in weight of each other? What we want to find out is whether the identical twins on the left are showing us more blue signs, meaning they're both agreeing at the same time.
On the right side, we expect to see more yellows, cos we'd expect to see more disagreement.
Thank you very much! Surprisingly, they're finding that genes play a part in some fundamental areas of our behaviour.
Do you support the same political party as your twin? Yes!Controversial! Do you support the same political party as your twin? Thank you very much.
If you are both believers or non-believers, show blue, but if you differ in your beliefs in God, show the yellow card.
When we look at this study now where we're asking about whether you actually believe in God, we see a real difference, because we see the identical twins agreeing much more than the non-identical twins.
So what this shows is whether you call yourself a Christian, a Jew, a Muslim is under environmental influence and the way you're brought up.
Actually when you go under that and you say, "How strongly do you believe in a God or an afterlife?" that actually, as well as an environmental component, has a genetic influence as well.
And that, I think, to most people is a bit of a shock.
If one of you has been divorced while the other hasn't These experiments are being repeated in 53 studies all around the world, drawing on tens of thousands of twins.
They consistently find that genes do shape our behaviour, our decisions and some of our most personal beliefs.
Our genes may even make us vulnerable to danger.
It's not sugar glass, ladies and gentlemen, this is actual glass.
So when you think it looks sharp and as though it might cut you, it's because it will.
Professor Fowler wants to know if there's a genetic component to one of our most formative personality traits, one which underlies most of the decisions we make in life - risk taking.
The question is, how tough do you think you are? Each twin has been separated from his or her sibling and asked to choose whether they have the courage to walk on broken glass.
What Professor Fowler is looking for is how many pairs make the same choice as each other.
Chris and Xand make up their minds pretty quickly.
I mean, I can see it's a bit dangerous, but I don't imagine it's going to be too bad, and I'm quite curious to see if it will hurt or not.
Presumably, they're not just trying to get us to tear our feet to pieces, so I'll have a go at it, yeah.
I think the glass looks very sharp.
It's hard to imagine whatever we're going to do, that I'm not going to get lots of pieces of glass in my foot.
But it's only glass in the foot.
I'm not going to die.
Are you a bit nervous about this? Yeah.
It's not painful, is it? It's just very, very, very frightening.
I'm a bit worried about him, are you worrying about me? No, I don't care about you.
I'm worried about my feet getting cut.
Hold on, are you holding an arm? I'm holding tight.
Don't see much blood.
If I could just sweepSorry.
I'm quite embarrassed that you were holding an arm, I don't feel You weren't holding an arm? No, I didn't hold an arm.
Well, it seemed sensible to hold an arm.
Sorry about that.
Astonishingly, just like Chris and Xand, eight out of ten identical twins made the same choice - both either took the risk or both refused to do it.
That's compared to just six out of ten non-identicals who chose the same way.
The results of the experiments are challenging Xand's view that he is completely in control of his own destiny.
Did you find when you did it that the identical twins make decisions that were more similar than the non-identical twins? We did in fact, and if we had to just estimate what percentage of the behaviour was accounted for by genes for this particular experiment, we would say it's about 40%.
Really?40%, really? That's amazing that you're saying that aspects of our personalities which I would normally think were shaped by environment, like how much we fear different things or how much risk we were prepared to take, you're saying there's a large genetic component to lots of our behaviours?Absolutely.
Everybody knows that eye colour is very genetic, that height is very genetic, but what the behaviour studies really tell us is that things like personality are also genetic.
This risk-taking experiment is a perfect example.
So what does the fact that we're both prepared to walk across broken glass tell us about other aspects of our lives? Well, risk is a fundamental personality attribute and it underlies so many things.
Entrepreneurs are people who take risks.
It underlies the kinds of political decisions you'd make, either as a voter or as a leader.
Think of a leader deciding to go to war.
It underlies the decision to divorce.
If you're in an unhappy marriage, are you going to take a risk and end up leaving that marriage? It underlies infidelity - the same kinds of decisions.
That's surprising to me.
I'd have thought that something like whether or not you get divorced would be much more informed by environment, experiences and what your wife was like, rather than your genetics.
It's not either/or, it's both things going on at once.
I'm not saying that it's 100%, but genes are very important for us to be able to understand risk-taking and the things that it affects.
It's remarkable just how many of our traits are shaped by our genes.
But for Professor Fowler, the theory that it's either our environment or our genes that make us who we are, is far too simplistic.
For a long time, we've had this debate, "Is it nature or is it nurture?" And I think that really what we're looking for is the way genes interact with the environment to produce the beautiful, complex social behaviours we see in human beings.
While we may be born with the tendency to act in certain ways, we need an event to trigger that tendency.
You look like you're building Fort KnoxShut up, shut up, shut up.
Neither the environment nor our nature work alone.
It's the way they affect each other that shapes our behaviour.
That interaction of genes and environment influences our behaviour in ways that can seriously affect our wellbeing, even our mental health - a problem that faces millions of us world-wide.
This is something identical twins Brittany and Stephanie found out as they both grew from happy children into troubled teenagers.
I've tried to commit suicide quite a few times.
First off I started jumping in front of cars and buses, and then I was drinking bleach.
I was under the influence of the thought that people would be better off saying goodbye to me very, very quickly than saying goodbye to me slowly.
They diagnosed me with anorexia.
I was put into hospital for nine weeks.
I had a nasal gastric tube and that drip fed me for a long time.
I realised later on that I was actually going to die if I kept going the way I was going, but it was never my I never wanted to die, because if I wanted to die there's so many quicker ways of doing that.
These days, the girls appear far from identical.
Stephanie's anorexia nervosa and Brittany's depression have transformed the way they look.
I feel really out of control.
I'm quite I'm really embarrassed.
Just really, I feel grotesque.
It's not a fun place, to be looking in the mirror.
I hate getting up in the morning and having to see that and as soon as I do, I don't want to see it.
I avoid reflective surfaces and I avoid mirrors until I can actually go and take control of my appearance.
Both the girls' mental health issues were triggered at the age of 11 when they moved from their home in Canberra for a fresh start in the country.
I didn't know how to deal with it.
I didn't This new situation seemed almost like a really bad dream, that I couldn't wake up from and I didn't know what to do in, and I was totally out of my element.
I had no idea how to live this way.
I wanted people to realise there was something wrong, and I had all these mixed emotions and it was very difficult, and I just channelled them into this one way of thinking of "I must control something", so I'll control losing weight and I'll just stop eating.
Stephanie and Brittany are not unique in their struggle.
In the UK alone, one in 15 people will suffer from anorexia at some point in their lives.
And one in ten of us will suffer from depression.
One of these mine?Oh, I don't know.
Twins hold important clues to help trace the genes involved in both these conditions.
We know that anorexia nervosa and major depression share genes.
We don't know exactly what the genes are, but we know that the same genes can lead to either anorexia or major depression.
What we see with Stephanie and Brittany is that they do share a perfectionistic temperament, they share a need to control how people react to them and to control their environment.
Their personalities are quite similar.
Professor Wade is a leading expert in psychological disorders.
She works with twins to understand the different ways in which our genes and our environment interact.
50% of low self-esteem is caused by genes and 50% is caused by the environment.
Now, that's an average, so for some people in the population the genes are going to be stacked against them in that they have more genetic risk, more geneticvulnerability for low self-esteem.
This is just about trying to draw a little bit of how you perceive what's happening in your life Working with identical twins like Stephanie and Brittany is helping Professor Wade develop specific treatments for these conditions.
Although their DNA's stacked against them, therapy is helping the twins take control in a positive way.
It's really important to understand that we can actually work with the environment to counteract our genes or to moderate our genes, to tone down our genes.
We know that we can improve people's self-esteem.
We know that we can actually treat people for perfectionism and decrease their perfectionism.
It means that they can not be a slave to their genes.
It's comforting to know that we can use our environment to help control our lives and battle against our more negative genetic tendencies.
But sometimes the balance between nature and nurture isn't so easily swung.
In fact, twin studies show us that in some rare cases, no matter how much you try, it's only a matter of time until your genes win out.
Take the case of Iain Satterthwaite, an incredibly healthy Englishman living in New Zealand.
My lifestyle is walking, water-skiing, kayaking.
I like to eat healthy, I try and get my five fruit and veg a day.
His identical twin brother, Paul, from County Durham in England, is ever so slightly different.
As for physical exercise outside of work, I don't really have much time or probably inclination because after a day at work, I want to relax.
I've got to the stage where I prefer exercising my right arm, rather than the rest of my body.
I try to keep off the caffeine, trying to keep salt-free as much as possible.
Too often, I like a full English breakfast and fish and chips.
Fruit? I prefer it fermented in bottles anyway.
Not surprisingly, two years ago, Paul had a heart attack.
At one o'clock in the morning, I woke up and the pain was really quite horrendous and it wasn't as though I could actually control it.
Paul's arteries were so badly clogged up, he had to have a stent put in to help the blood flow.
He was lucky.
Heart and circulatory disease are the UK's biggest killers.
In fact, someone dies of it every six minutes.
During one of my phone calls to the UK to find out how Paul was, I got talking to his nurse and his nurse said because I'm an identical twin, and need to get checked out and make sure that I'm fine.
I said, "Why?" I said, "I don't smoke, I get exercise, I eat healthy.
" Paul doesn't do those sort of things.
The nurse said, "You've got to get yourself checked out.
" Can you roll onto your left side Iain now has regular health checks because when he followed his nurse's advice, he got a shock.
Although he thought he had nothing to worry about, after just a few tests, he was sent straight to the operating table.
I was told I had been heading for a major heart attack, so that was a bit of a shock.
I was so upset, because, after all of this time doing the right thing, I find out that I'm no different from my brother.
Despite a marked difference in environment and lifestyle, the twin brothers developed the same heart condition at the same time.
Cardiologist Dr Victor Chen performed Iain's surgery.
Surprisingly, his twin brother had a blockage in that exact same segment.
It's hard to imagine their shared genes didn'tplay a part in this.
A recent Swedish study of twins confirmed that genetics played an important role in the development of heart conditions.
There was a large study of over 7000 patients, where, if heart disease developed at an early age, the other twin was at extreme risk of also developing heart disease in the next five to ten years.
That risk is something like 20 times what we'd otherwise expect.
For Paul and Iain, their genetic destiny prevailed regardless of their environment.
But cases like this are incredibly rare and more often than not, our lifestyle does play a pivotal role in whether we get ill.
We know for sure that not smoking reduces the risk of heart disease.
Unfortunately in this case, genes seem to have been the major influence on developing heart disease in these twins.
Heart disease is only one of hundreds of health conditions studied with the help of twins.
Every year, dozens of scientists flock to the aptly named town of Twinsburg, in Ohio, for there largest annual gathering of human clones in the world.
Sometimes we think we're not the same, seeing all these other twins.
They're like replicas.
We've from the Philippines.
We're police officers with the rank of a general.
Two-star general, see? This is our 19th year consecutive, and we just like coming to make new friends.
It's like a family so you come backIt's like a family reunion.
But it's not just a social gathering.
Keep biting down Just like the party at St Thomas' Hospital, scientists here are studying how genes and the environment interact with each other in everything from cancer to autism, back pain to Alzheimer's.
You eyes are really good.
We're from Hungary and we're identical twin doctors, from Semmelweis University.
We're conducting an international twins study regarding heart disease.
We're from the Centre for Education and Drug Abuse Research.
We're here today to test twins for their alcohol perception.
Skin appearance.
Facial ageing.
Measuring hearing in children at the Twinsburg festival.
Comparing human clones helps them pin down the specifics of each condition.
Some are more determined by our genes, others by our lifestyle.
The twins are very interested in research.
They seem to understand how important they are for science.
Everyone gets involved, from the age of five to 75.
Doing justice to their title of science's favourite subjects.
We've got some gold medals for you this year! First place medals for Grace and Jasmin from Ohio.
Most alike females, 7 and 8-year-olds MUSIC: "Mamma Mia" by ABBA ECHOING:Oh, my gosh! I can hear myself BOTH: # I've been cheated by you Since I don't know when # Separated twins Mia and Alexandra have been together for three days.
BOTH: # Mamma mia! Here I go again My my, how can I resist you? Mamma mia! Does it show again? My, my, just how much I missed you Yes, I've been broken hearted Blue since the day we parted Why, why, did I ever let you go? Oh, my goodness! I'm walking backwards so I don't know where I'm going The girls are now so close, they've decided they only want to dress in the same way.
She's been with Alexandra night and day and yet, they just want to be together.
I'd think that that speaks to the genetic factor.
They're so much alike, so much in tune with each other, that they want to be together.
This one? OK.
So, how old are you guys?Six.
The families have been joined by Dr Nancy Segal, a world expert in twins raised apart.
Hold your arms out.
Good idea! 'I'm interested in Mia and Alexandra for a number of reasons, 'they're identical twins, the same genes in totally different environments.
' This gives us an ideal opportunity to see the extent to which genes underlie behavioural and physical and medical characteristics.
Mia and Alexandra, just by being raised apart, are a wonderful natural experiment.
Alexandra, you look beautiful.
Dr Segal has studied a number of twins who met as adults, but this is her first opportunity to observe separated twins as they grow up.
Do you guys have any other brothers or sisters?I have a big brother.
How about you, do you have any brothers? I have a sister, that's her.
Two sisters Hi, you guys.
Nice to meet you, sisters.
It's a great scientific experiment.
These two were raised apart but Alexandra was raised with two sisters.
How similar is she to her two sisters? She'd pick up something from them and learn, of course, some behaviour but when I see them now, they are are more alike than she will be like her sisters at home.
That's such an important observation.
She's lived with two sisters all her life and she's more like the sister she just met.
It's very hard to explain that without thinking about genetic factors.
You want a snow cone?Yes, please.
A snow cone? BOTH: Ple-e-e-e-ease Watching the girls behave in such a similar way is raising big questions for Angela.
Seeing the way Mia and Alexandra interact together and seeing how much genetics plays a role in who they are makes me wonder how much control I really have as a parent.
Look, look Aaah! Aaaah! They both have a little bit of an attitude and they are very strong-willed, and I'm not sure if any parenting style or techniques would really affect certain things that they do.
They're going to be the way they are no matter what.
So it makes me realise I have to step back as a parent and observe her for who she is, so that I can help her become who she wants to be, maybe not so much who I might want her to be.
High five! Whoa-oh! Good job! Mia.
High five, yeah.
After an amazing week together, Alexandra's stay with her twin Mia is coming to an end.
For the girls, having to say goodbye to each other is difficult to understand.
What would you like her to do? To stay here.
To stay here? Would you like her to move in across the street someplace?Yeah.
It's just so hard thinking about them being so far away.
It's going to be really hard for me to say goodbye to them.
But I'm glad they're part of my life now.
SHE SOBS I'm so sorry Eg asker deg That's "I love you.
" Eg elska deg ALEXANDRA WHISPERS CORRECTION OK! Eg elskar deg.
I think they are more than just friends.
There are really sisters now.
I think they will miss each other a lot.
Alexandra.
We have to go.
ALEXANDRA SOBS THEY TALK IN NORWEGIAN You want to give her a hug? ALEXANDRA SPEAKS IN NORWEGIAN SHE SOBS What is she saying? "I'm going to miss her.
"I don't want to go.
" It's very sad for the girls to be separated once again but both families have vowed that this is just the beginning.
Separated twins Debbie and Sharon were not as lucky as Mia and Alexandra.
They only met at the age of 45.
These are saints But all the time they spent apart didn't change their remarkable connection.
I was brought up Jewish.
And I was brought up Catholic or Christian.
We're both religious and find a lot of solace and comfort in our faith.
God brought us together after 45 years.
Debbie didn't know she was adopted.
I always knew I was adopted but we didn't know that there was a twinAnother one of us.
Coming face-to-face with each other for the first time was an extraordinary experience.
People always say, "So it was like looking in a mirror.
" No.
No, when you look in a mirror you know that's you.
It's like, if we're talking and suddenly your face is on me.
It's like you're looking at yourself on another body.
And a stranger.
It's too weird to even explain.
Despite the shock, their similarities made it feel like they'd always been together.
Debbie and Sharon's experience could give Mia and Alexandra the hope that distance will never weaken their special bond.
We just laugh at everything Everything .
.
and especially when we say something at the same time it still like a novelty to us, I guess, and our families get really annoyed by it.
THEY LAUGH My husband said, "It's like my wife in stereo!" The very latest in twin studies hold the promise of a world where we can all maximise our strengths and improve our weaknesses.
BEEP Ohh! Go back! They suggest we'll be able to predict our talents by looking at our genes.
Yeah! It was close, it was close.
So, very simple task - when we say "go", just turn over the instructions, read them and follow them.
And are we being timed? Is it a race? We are timingyou.
OK, we're racing.
Dr Yulia Kovas from Goldsmiths College in London is studying the influence of our genes on our ability to learn.
This one.
Are you ready? Go.
She's giving Chris and Xand an applied maths calculation.
They have to work out what 10% of £5.
20 is and subtract it from the total.
The calculation is quite complicated, so a lot of people are getting it wrong, so let's see how they're doing.
But will the boys get it right? And, more importantly, will they work out the result within a similar time? In other words, are they just as good as each other at maths? Right, finish.
Finished?Yeah.
OK, let's have a look.
68.
Correct! Correct!I beat you by about three seconds.
Yeah, OK.
Both correct.
You're slightly faster, so you're the winner.
Chris and Xand are only three seconds apart from each other.
Much like most identical twins tested, their result is incredibly similar.
Do you think there is a genetic component to how good you are at maths? I don't think there is any doubt about it.
We've done research all over the world in many twin studies, adoption studies.
We know there is a contribution from genes.
What's surprising to me is that runs counter to everything I was told throughout my education.
The more you studied, the better at maths you got.
Maths feels like something where you can practise it and get better.
If you don't do well, it's cos you haven't done enough work.
That's a good point.
Genetic component is not just that your brain is somehow better at doing this.
Genetic component also explains differences in why people are not interested in maths, not motivated in maths, interested in other things.
The goal is to find Dr Kovas is hoping this research could eventually change our school system into one of education tailor-made for each child's needs.
.
.
We will be able in the future to take a little bit of DNA from a child, or anybody, and say, "This person has a high risk of being bad at maths.
" And so we will be able to enhance and suppress genetic predispositions by using this information.
That's amazing.
The idea that you would take a child and do a genetic test and you could say that one child would benefit from one kind of maths education, and another would benefit from a different approach.
Is that it? That's the hope that we have.
While this is controversial, it's just the tip of the iceberg, as twin studies are also opening up the promise of tailor-made medicine.
Go.
Go.
Right down.
One key area of research is in pain relief.
This is awful.
In this test, researchers are investigating whether there's a genetic component to our tolerance to pain.
They're asking identical and non-identical twins to keep their hand in ice-cold water for as long as possible.
How long did you go? About ten seconds.
Ten seconds? You're a wimp! Oh.
.
Identical twins ended up with three times more similar results compared to non-identical twins.
They were strikingly similar.
What this tells us is that genes are responsible for most of the variation between people in how they can put up with pain.
Can you make it a bit colder?! Now, by comparing the data between thousands of individuals, Tim Spector is looking for the exact genes responsible for pain tolerance in all of us.
We know there are huge differences in the way people respond both to pain and to painkillers.
If we can personalise this and be able to tell, with these genes what's the best drug for you, we can help that person and also stop taking drugs unnecessarily, which won't work.
I was wincing at the beginning, but now I'm dying.
Oh.
But for Chris and Xand, the pain tolerance test isn't going to plan.
Ah! .
.
and then what you're doing now is your sort of endurance Unusually, Chris and Xand are not handling this test with equal success.
You're finding it easier and easier, are you? Just to tease your brother.
So how's it feeling for you? I'm about done actually.
About done?I really am.
When you are, take it out.
Don't tell your brother when you do it.
He can carry on for a few hours.
Xand, if you take it out, I don't know if that's gonna make me take it out or not.
Yeah, yeah.
He's not telling if he is or not.
So you think you could keep going for another couple of hours, do you? OK.
You all right?Yeah, I'm all right, I'm all right.
Yeah.
It's all right.
Just take some deep breaths.
I think I would have fainted, if I'd stayed doing it any longer.
You look a bit pale.
Are you all right? Did you have a bit of a faint? You look awful.
It really hurts still.
Gosh, look at you.
It may not be the result that Professor Spector anticipated, but in Chris' case, there's a particularly strong reason for his tolerance to the cold.
I've spent a lot of time in the Arctic.
Umand for Arctic training, you have to spend time jumping into the Arctic ocean, while it's covered in ice - the sea being -2 - and then getting out and rolling around in the snow, so I have a certainYou're conditioned.
I have confidence that no harm is gonna come to me.
In this aspect, Chris and Xand are clearly very different.
It seems that in relation to pain tolerance at least, their experiences in life outweigh their genetic similarities.
This is music to Xand's ears.
That does to a certain extent prove me right.
That was a sort of triumph for personality over genes when we were doing the pain test.
I really failed before you did and that's not genetic.
That's just me not being as tough as you.
And although I would have rather won, I was quite pleased to see that you could overcome your pain and get through it and that seemed to work well for you, whereas I was suffering.
So you interpret any difference between us, cos we have the same genes, you say that any difference between us is due to environment and that gives you some hope that you could that one of us could become a better person in some way? No, that I'm not I'm not so constrained by my genes.
I'm not fated to it.
As Chris and Xand just demonstrated, no single pair of twins is ever completely identical.
And that's what we'll explore in our next programme, because the differences between identical twins can be just as revealing to scientists as their similarities.
Susan's really soft and gentle and understanding.
I got a temper that could beat a kettle.
While similarities have shown us the importance of our genes, differences will reveal exactly how the environment can affect who we are and how we change throughout our lives.
So why are some of us fatter than others? Oh, my God.
I'm going to be as heavy as she is and I have to wake up now! What influences the way we age? Even though she was born five minutes ahead of me, I'm ten years older than her.
And what makes us straight or gay? No-one has ever asked if I'm gay because my brother is.
We'll follow Chris and Xand again as they go in search of the experiences that hold the key to their own individuality.
The key statistic here is the percentage of fat, difference between you.
Xand has 30 and you have 19.
God, that's terrible, isn't it? And we'll meet two brave little girls, identical twins, who've been helping scientists understand what causes leukaemia.
Under chemotherapy, Olivia lost her hair, so straight away, they lost what to me was their twin-ness.
I felt she was going to She was nearly going to die.