My mo di twins are not identical

heaven22tw · May 2014

My mo di girl are now 8 mo old and they are not identical. They have different noses, one has dimples, and their head shapes are different, and ones eyes are bigger. They definitely are very similar but even strangers can tell the difference. It WAS confirmed mo di in the hospital lab testing post delivery, and due to 5 previous losses was monitored from the very beginning and we didn't even see a separation until 14 weeks w a very high resolution ultrasound. Im so confused. Does anyone have any insight? How is this possible?

Rynleigh · May 2014

Start with having them tested to confirm your suspicion if they haven't had the actual DNA test (examining the placenta and confirming that it is a single placenta isn't the same as testing DNA). You cannot claim that your children are not identical simply because you don't think they look enough alike - your children can have identical DNA and still not look "identical"... you can even have some genes flipped "on" in one twin and "off" in another. If their DNA is identical, they are identical regardless of whether they look identical or not. Genes being flipped on or off or even random mutations in one twin but not the other can affect that.

If you get a DNA swab done for them and that test does in fact prove that they are not identical twins, there are two possibilities:

1) Your twins may have had their placentas fuse very early on, causing it to appear that they had only one placenta - this is the most likely case in every circumstance of misdiagnosed di/di as mo/di, and it means that your twins never actually were mo/di - they were di/di with a fused placenta.

2) Your separately fertilized eggs fused extremely early, in the zygote or blastocyst stage - this is a *hypothetical* situation that could theoretically be possible, but it is not a proven theory because it has not been observed or repeated.. the hypothesis is that with extremely early fusion, the twins would develop only one placenta.. this hypothesis is used to explain extremely rare incidents where proven fraternal twins experienced true twin to twin transfusion syndrome, a syndrome that can only occur in the event of one single shared placenta.

There is a third scenario in the case of boy-girl mo/di pregnancies where the twins can be identical, but one twin does not receive the Y chromosome - which results in X monosomy, or Turner Syndrome. They are still identical twins, but because one twin is missing the Y chromosome, they are biologically female, while their brother is biologically male.

heaven22tw · May 2014

Wow thank you ...I just assumed if they are identical they looked identical. I will follow up with the DNA testing.

heaven22tw · May 2014

On a side note the placenta was tested and confirmed it was never fused:)

Lisasugar · May 2014

Please let us know the outcome after the DNA test.

24karat · May 2014

From my understanding it is EXTREMELY rare for mo-dis to be fraternal. It's more likely and possible for di-di fraternal twins to fuse placentas and be mistaken for mo-di, but it sounds like you already have that ruled out.

Identical twins share the same DNA but they never look 100% alike. Mine have a slight difference in size that's been present from the start and makes them look pretty dissimilar. They also have different head shapes, complexions, builds, and hairlines. Most people have very little trouble telling them apart. We haven't done testing to confirm that they are true identical twins because the chances are so slim that they're fraternal. We discovered them at 6wks and they were initially treated as mo-mo, no membrane was discovered till 2nd tri and it was perpendicular to the placenta, no peaking or other indications of a fused placenta.

raraavis28 · May 2014

@Rynleigh and @kjkarats03 have very good explanations. People have told me that my boys "must not really be identical" because I've said I've never had trouble telling them apart (besides a notable size difference, they just seem so very different to me, even though they were also mo/dis). I've kinda come to dislike the term "identical twins" because of this....it gives people the idea that these kinds of twins are always going to look like carbon copies of each other, and that's just not the case.

pea-kay · May 2014

Differences in blood flow in utero can also make a big difference, as well as positioning in utero.

ceechie · May 2014

pea-kay said:
Differences in blood flow in utero can also make a big difference, as well as positioning in utero.

I get the positioning aspect, but have never heard about blood flow. Can you elaborate? It's very interesting...

pea-kay · May 2014

If one baby has restricted blood flow in utero, that can mean different development rates, different sizes, etc. I'm no scientist so not very good at explaining.

But it can depend on when blood flow is restricted and how much, etc.

ceechie · May 2014

pea-kay said:
If one baby has restricted blood flow in utero, that can mean different development rates, different sizes, etc. I'm no scientist so not very good at explaining. But it can depend on when blood flow is restricted and how much, etc.

Totally makes sense. I was thinking way too hard about that! haha

ceechie · May 2014

Can you post a pic, @heaven22tw‌? I'm super curious to see them...

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My mo di twins are not identical

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