The identical triplets born in a Houston hospital are not only special for their parents but also for science because according to doctors they are “one in a million”. Though use of fertility treatments like In-vitro fertilisation (IVF) has contributed in increasing the twin and triplet population but they are common because they are fraternal that is born from multiple fertilized eggs. Adding to this, moms over 30 tend to ovulate more than one egg giving rise to more twins. So to understand why identical triplets are rare, you will have to understand the difference between fraternal and identical twins.
Fraternal or Dizygotic multiples occur when more than one fertilized egg becomes an embryo whereas identical or monozygotic multiples occur when the egg divides ‘after’ it gets fertilised. This implies that monozygotic multiples share the same DNA. So it is common when two sperms fertilise two eggs but for identical twins the zygote separates in two parts and when it is triplets we are talking about, the zygote needs to split ‘two’ times and you can guess how rare that is.
The general confusion that when we see so many identical twins then how come we don’t have that many examples of identical triplets is rooted in the age old myth that identical twins run in the family. Well fraternal twins may be, but not identical ones. According to researchers, fraternal twins may run in a family because of women in a particular family sharing a particular genetic trait that makes them release two eggs during an ovulation cycle.
But till now, no findings imply a genetic predisposition towards zygote splitting. This is the reason that if you have a twin sister or have twins in your family, doesn’t mean you have identical twins. It simply implies that you have a tendency to ovulate two or more eggs in a cycle (which doesn’t always results in conceiving twins always).
You just have to think, that if it was the case that identical twins ran in a family, then identical twins would be more likely to have identical twins, and there would be many more identical twins and hence the chance of many more identical triplets. So in reality, it is a very random phenomenon, so much so that three births per 1000 worldwide are identical twins. This is why identical triplets are one in a million. So now you know, why those triplets born in Houston hospital are so very special!
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Author: Technology Blog
