# Identical twins CAN be opposite genders!!



## Aria

Don't believe me? Well, don't believe me, believe National Geographic. A few months I saw the NatGeo special, In the Womb: Multiples. This video excerpt from their site says:

 Identical twins are almost always the same sex, but surprisingly there are a tiny number of boy-girl monozygotic twins. They result from an egg that contains an unusual mixture of sex chromosomes, not the usual XX for a girl, and XY for a boy. Occasionally an egg contains three sex chromes, two X's and a Y. But if the egg divides to produce monozygotic twins, a chromosome may be lost in the process, leaving one embryo with a girl's XX combination, and her monozygotic twin as an XY boy.​
This can also happen when the egg is fertilized with the male chromosome, making an XY egg, that splits into two, with one of the embryos dropping the Y, making her an XO girl, resulting in Turner's Syndrome.

Identical twins start off as one egg that splits, but the two separate embryos don't always develop identically. More and more experts are beginning to refer to these twins as monozygotic twins instead of as identical twins.

There are only a few documented cases in history of boy-girl identical twins, so it's not surprising most people have never heard of it. I only learned of it while watching that full NatGeo special. Interesting that this CAN actually happen, no?


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## Tasha

Wow. No one would ever believe them that they were indeed identical twins


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## Waiting2bMommy

wow thats crazy!


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## tansey

Wow that's really interesting!


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## Aria

Amazing, is it not? This is why more doctors are starting to call identicals monozygotic instead. Even when they're the same gender, one getting a little bit more oxygen and the other a little bit more nutrition can result in babies that don't look 100% alike.


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## FsMummy

yeh i watched that the other day they called them semi identical


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## princess_bump

oh wow! x


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## sailor

Hi aria you are indeed right. I lend out this dvd in my multiple birth classes in Reading and parents to be find it a fascinating watch.


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## vineyard

I know someone who has triplets and 2 of them are identical twins of opposite gender.


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## 2and2

I'm convinced my b/g set are identical. They look so similar. It was about a month ago that this was pointed out to me


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## twinmom07

It is crazy, we saw that special when we were expecting J&E.
We have a mom in our multiples club who has b/b identicals, one has CP and the other doesn't! But they are 100% sure they are identical as the state did testing for them... some twin study thing.


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## Always&amp;4ever

Wow I never knew that


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## AppleBlossom

I know a set of identical twins that are different sexes :)


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## Char&Bump-x

I want to see them! lol


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## broodylocket

wow cool didnt know that!


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## morri

Thats quite cool. Especially you can see how the same material turns out as boy and as girl. I would be interested in seeing pictures of them :D


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## Blob

Wow thats crazy, nobody would ever believe you if you told them.


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## vineyard

Its so rare and usually involves a chromosomal abnormality. For instance, the family I know the twins have male chromosomes but one came out totally female, female parts and all. But, during chromosomal analysis she was male. So, they are kind of opposite genders but not really. It's wierd.


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## Gwizz

Wow, just shows the human body is capable of anything :)


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## Bunnipowder

Id never of thought that!


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## morri

interesting site :) leads also to more interesting topics such as polartwins which is not proven yet but interesting in any case :)


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## 2and2

I eventually has mine tested and they are classed as 'identical'


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## chetnaz

I have this dvd also and have heard of identical boy/girl twins so when i went for my gender scan, the doctor checked one twin and said they're boys, but I insisted he checked both, just in case. At first I thought it would be great to have one of each gender but then again doesnt it mean there are chromosonial abnormalities? Would there be problems health wise? Kind of made me think really...Glad they are of the same gender - you get so many questions from people abould twins as it is - imagine trying to explain boy/girl identicals!


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## vineyard

chetnaz said:


> I have this dvd also and have heard of identical boy/girl twins so when i went for my gender scan, the doctor checked one twin and said they're boys, but I insisted he checked both, just in case. At first I thought it would be great to have one of each gender but then again doesnt it mean there are chromosonial abnormalities? Would there be problems health wise? Kind of made me think really...Glad they are of the same gender - you get so many questions from people abould twins as it is - imagine trying to explain boy/girl identicals!

Yes in order to have boy girl identicals theres chromosomal abnormalities. For instance, the pair I know of has 1 boy, 1 girl. Both have the DNA of boys. However, the girl has a vagina despite the chromosomal makeup being male.


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## mamato2more

I asked my midwife about this a while back. She said in most cases, they were hermaphrodites..Very sad really


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## BeckyD

I don't think you really want to have opposite sex but identical twins.

We're expecting identicals and I have my 18 + 4 week scan on Thursday. I'm really hoping we find out the sex - will be happy either way but I just want to know!


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## chetnaz

BeckyD said:


> I don't think you really want to have opposite sex but identical twins.
> 
> We're expecting identicals and I have my 18 + 4 week scan on Thursday. I'm really hoping we find out the sex - will be happy either way but I just want to know!

Oooh how exciting - i remember how impatient i was to find out their sex! Let us know how it goes. And be prepared to be stopped ALOT and all the questions are even more intense with identicals.


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## bek74

vineyard said:


> chetnaz said:
> 
> 
> I have this dvd also and have heard of identical boy/girl twins so when i went for my gender scan, the doctor checked one twin and said they're boys, but I insisted he checked both, just in case. At first I thought it would be great to have one of each gender but then again doesnt it mean there are chromosonial abnormalities? Would there be problems health wise? Kind of made me think really...Glad they are of the same gender - you get so many questions from people abould twins as it is - imagine trying to explain boy/girl identicals!
> 
> Yes in order to have boy girl identicals theres chromosomal abnormalities. For instance, the pair I know of has 1 boy, 1 girl. Both have the DNA of boys. However, the girl has a vagina despite the chromosomal makeup being male.Click to expand...

I think that is sad. This poor baby is in everyway a boy but with a vagina, she will grow up wanting to be a boy as she has the DNA and chromosones of a boy, sad.....



mamato2more said:


> I asked my midwife about this a while back. She said in most cases, they were hermaphrodites..Very sad really

I agree, to have the body parts of one gender but the DNA of another, I feel for those little babies especially as they get older.


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## vineyard

2and2 said:


> I eventually has mine tested and they are classed as 'identical'

Do your twins really have different birthdays!? If so, that's super neato!


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## bek74

vineyard said:


> 2and2 said:
> 
> 
> I eventually has mine tested and they are classed as 'identical'
> 
> Do your twins really have different birthdays!? If so, that's super neato!Click to expand...

I noticed that also.... very cool.


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## amie-leigh

vineyard said:


> 2and2 said:
> 
> 
> I eventually has mine tested and they are classed as 'identical'
> 
> Do your twins really have different birthdays!? If so, that's super neato!Click to expand...

my cousins are twins but one is the 6th may and the other the 7th may dale was born at 11:55pm and euan at 12:05am exactly 10minutes apart :haha:


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