What are the theories as to why a fertilized egg sometimes splits on its own to create identical twins?

Question

What are the theories as to why a fertilized egg sometimes splits on its own to create identical twins?

Answer 1

It's an intriguing question and one that I have often thought about in passing.  As I understand it, the fertilized egg (zygote) normally splits off while traveling down the fallopian tube on its way to the uterus. There must be something that happens to the zygote membrane itself that triggers a second genesis.  It might have something to do with the egg's own genetic program of development.  Recall that at the moment of fertilization, it is the penetration by the sperm cell that physically triggers an intrinsic developmental program in the egg itself. Once this metabolic pathway is activated, this intrinsic developmental program is what tells the newly fertilized egg to undergo mature mitotic cell division.  Perhaps, some where along the way, this intrinsic developmental program pathway gets triggered a second time, maybe by a random mutation occurring in one of the genes that controls and regulates that function.  If that happens to be true, the activation of this developmental program might be just enough stimulus to tell the whole zygote to split and form two zygotes. The reason that I think there might be something to this idea is that, research shows that when a normally fertilized egg is physically split in the laboratory, the two zygotes develop pretty much in the same way. However, if you take a developing zygote and not split it, but physically extract just one or two cells from it, these newly freed cells will also develop into an identical twin except that, because the freed cells were very much smaller than the zygote as a whole, the individual's formed by these freed cells are typically smaller than the individual that fromed from the zygote proper.

This suggest to me that, whatever it is that triggers ID twining, it is a mechanism involved in very early development occuring sometime just after fertilization.

See: New theory on the origin of twins -- mutations within embryo

http://findarticles.com/p/articles/mi_m1...

Identical twins may form after embryo collapses

http://www.msnbc.msn.com/id/19588314/

Also, because identical twins originate from a single egg cell and from common DNA, there is a thing called "entanglement". It is a very powerful aspect of quantum physics that expresses itself in all matter and energy, that may have much to do with whatever mechanism involved in creating physical twins, and, in the conscious commonality seen in many human twins.

See: Genetics and the Environment -- Twin Studies

http://www.libraryindex.com/pages/2233/G...

Quantum Mind - Wikipedia

http://en.wikipedia.org/wiki/WikiQuantum...

ENTANGLED MINDS: Extrasensory Experiences In A Quantum Reality

by Dean Radin

ISBN: 13-978-1-4165-1677-4

Answer 2

"As far as scientist can determine, there is no reason why the egg splits - it's a spontaneous and random occurrence. One theory is the egg ovulated by maternally mature women (Moms over 35) is not as flexible as it is in younger moms. When a fertilized egg begins its natural division process in creating a baby, the egg actual 'breaks' (or splits) into two instead of dividing."**

I am not an expert. Just a lowly medical transcriptionist trying to learn as much about the medical field as I possibly can on my own merit because I cannot afford to go to college. So I do my homework and my own little research projects online.

Hope the website below helps to answer your question, however, it was only one theory.

Good luck,

AtlantaDoll