Different Sex ID Twins..

Okay before everyone says "No Way".. (which is what I said cause I had never heard this before.) But last night we watched the National Geographic In The Womb: Multiples and belive it or not, their are rare identical twins that are opposite sex.. It happens after the egg splits, resulting in only the one egg dropping a gender chromosome...

So I had to check this out (SERIOUSLY think of how many of people just assume B/G means fraternal, this puts a whole new spin on things) So I found it on Wikpedia and here is the quote to discribe it more:

(On extremely rare occasions, an original XXY zygote may form monozygotic boy/girl twins by dropping the Y chromosome for one twin and the extra X chromosome for the other. Some biologists also believe in the possibilty of the egg splitting first, then the two conceived eggs are separately semenated, resulting in identical appearance, but different sex)

Wow... Who'd of thunk'd it, huh?

 

I also heard of this too...I thought it was out there but it's true. My NST nurse asked if my boy/girl twins were fraternal or Identical and I looked at her with this crazy look and she said it's possible and I've seen it before. Intersting!

 

I think in that case the girl baby has problems - life threatening problems.

 

There was a long discussion about this when the program first aired. I believe the gist of the discussion is that a boy and girl can come from one egg which makes them monozygotic but NOT "identical" (obviously ). The documented cases involve girls with Turner's Syndrome (only one X) and a normal XY boy. The National Geographic program should not have presented the theoretical possibility for two normal children to come from one abnormal (XXY) fertilized egg stating it as a known fact. They should have used the documented cases of a normal boy and Turner's girl to explain opposite sex monozygotic twins.

 

I'm ticked that they aired this again without clarifying things... Like the pp mentioned...the extremely rare case of this involves a very sick little "girl"... most of the time they pass away soon after birth..when they do survive they have lifelong issues. I was upset that in mentioning this case NG showed a very healthy looking g/b set of twins who looked a lot alike...that gives the notion that this is a common thing...and that if you see a set of b/g twins that look alike they might be id. Chances are you have never and will never run across a set of twins with this issue. We did have a mom on here whose girl twin suffered from this syndrome...I believe she passed away. But it's extremely rare...and very sad. Honestly I think NG should have just cut this part of the program since they didn't have enough time to address it adequately. They probably did a whole lot to confuse yet another portion of the population on how twinning works. But I'm finding that a lot of NG articles spin things in a manner that suits their particular fancy...dramatizing things that really didn't or don't occur that simply.

I must say there are theories out there on how normal b/g id. twins could occur...but to date there has never been a documented occurance of it...and it would be extremely difficult to prove.

We had a whole big thread on this when the NG program came out back in January or February. Just irksome that they could flippantly mention a possible twin combination that just isn't all that simple. I think it was very misleading.

 

QUOTE(dmarie @ Sep 22 2007, 12:39 PM) [snapback]418703[/snapback]
I also heard of this too...I thought it was out there but it's true. My NST nurse asked if my boy/girl twins were fraternal or Identical and I looked at her with this crazy look and she said it's possible and I've seen it before. Intersting!


I hate to let you down...but in all likelihood this nurse is severely uniformed on id. versus fraternal twins... You can safely bet that 99.9% of b/g twins are fraternal... there have been NO known cases of healthy b/g identical twins documented.....at least this is what we determined in our searches this past January... and one of the ladies who popped on there did know a lot more about genetic/biological issues....she was pretty well informed about it. For a nurse to make an offhand comment like that...I'd be willing to bet her idea of "identical" means "look alike"...yes there are plenty of b/g twins who look similar...the same as there are plenty of siblings born in different years who look very similar, even brothers and sisters.... but this has nothing to do with being identical!! And any set of truly "identical" b/g twins that this nurse may have run across would have involved a very sick little girl.

 

What is Turner Syndrome? Do all girls with it die early?

Tiffaney

 

If you want to know more about Turner Syndrome, go to the search engine and type in Turner Syndrome and you'll find lots of info and lots of different websites. I would type it but it's to much. Hope this helps!

 

QUOTE(Shasta @ Sep 22 2007, 05:54 PM) [snapback]418960[/snapback]
If you want to know more about Turner Syndrome, go to the search engine and type in Turner Syndrome and you'll find lots of info and lots of different websites. I would type it but it's to much. Hope this helps!


ditto on this...but the short version from what I remember from the thread in January... it's basically when a baby is missing the dna information for gender...by default the baby is a "girl" (basically what happens is that the baby loses the Y part of the chromosome when it comes to gender determination...so all that is left for that part is the mother's X, but in reality the "girl" should have been a "boy" and is now missing critical dna for the correct formation of all the necessary parts.) ...but if I remember correctly, the child actually has no ovaries or uterus.... Also impacted, I believe, are growth hormones. I believe, stunted growth is common with these babies. I'm pretty sure there is a host of other possible issues as well. No, not all children with Turner syndrome die... but many do. And I imagine that living with the condition is very painful, physically and emotionally. If I were a parent whose child suffered from this I would be furious at NG for so casually mentioning b/g identical twins as if it's a normal, happy thing. I could be wrong, but I believe Turner syndrome can occur completely independent from twinning... although I wonder if some of these are the result of vanishing twin...I'd have to do more research on that one.

 

QUOTE
We had a whole big thread on this when the NG program came out back in January or February. Just irksome that they could flippantly mention a possible twin combination that just isn't all that simple. I think it was very misleading.


Ditto that, especially because now there'll be hoards of ignorant people in the grocery store who want to argue with us about zygosity of our twins! *sigh*