Our boys are identical twins. They were conceived naturally. Identical twins have always been "the twins that happen for no known reason."
You don't hyperovulate 2 eggs like Fraternal twins, etc. An egg splits, and no one knows why. I came across a blog tonight that had this link in it! It states that there is research being done on why the egg splits.
They have found an enzyme in sperm that causes the egg to split! Of the people tested, 99% of the men had the enzyme! HOW NEAT! I absolutely love researching twins.
Here is the information;
<< Now, does the research seem to indicate that this enzyme plays a role frequently in id twinning, far more frequently than geneticists have believed up until now, or is this still for only a small percentage of id twins? Also, you said the chance of repeat ids is as great as the chance of repeat fraternal, yet both you and I know women with 2 spontaneous sets of frats. (Of course, that's hardly a statistically sig sample) But, I've never met anyone with 2 sets of ids, nor have I heard of it. >>
Thus far, the research shows that the enzyme is directly responsible for causing the splitting of the chromosomes, which results in the division of the cytoplasm which results in two eggs! There are a few (about 1%) that have alluded us so far and have shows no sign of the enzyme despite the fact that twins resulted. Thus, we have concluded that identical twinning can also be a random event. But in about 99% of the people tested, the enzyme is apparently the culprit. So, 99% is a darm good yield! So, according to our research, it is not a small percentage but almost the entire percentage.
And yes, this study has been repeated already, but very, very little money is put into this research, so most of it is done on our own time. The reason for this is there is little to no medical advances that can come out of the research, just info and most of the money on medical and genetic research is for improving the outcome of diseases, etc. So, that is why it may be a while before this research is completed. We have to get about 5% of the public who have twins to complete our research (not all will go through tests, some will just answer questionnaires) before we can say that this represents the entire population, so you can see that this will take a while!
I have been working on this theory for some time. Ask people on this post nd I guarantee that you will meet peolpe who at least know of someone who as two sets of identicals. I know 2 people out of hundreds that have more han one set of fraternals and about that many in our research that have two ets of indenticals. There is a woman in Australia that has three sets of identicals (yes, with the same hubby!)! I think that hyperovulation is more frequent than identical twinning because it depends entirely on the woman and not on the husband, but identical twinning can sometimes be related to both, about 90-10 to 80-. It may also depend on many different things. The divorce rate for parents of multiples is very high. Identical twins tend to have more birth complications that fraternal twins, so that also can incease the divorce rate, as parents of sick children/babies seem to divorce more readily. If that being the case, the husband that caused the identical twinning is no longer in the picture and twins thus may not recur.
Also, many, many parents who have twins do not have more children, for obvious reasons. This also, that this enzyme may or may not manifest itself at every conception. There could be numerous reasons that the gene that turns the function or production of this enzyme on or off, as in diet, drugs, health, etc. There are so many factors and we have only scratched the surface.
It will be years before we can tell you what drugs, etc. influence the expression of the gene or the action of the enzyme.
Also, we see this enzyme in different races more frequently than in others.
We very, very seldom see this in the black race, but see it almost entirely in the oriental race. We see it about 50-50 in the caucasion race. It is almost non-exsistent in the Jewish race. So you see, many factors can increase or decrease the frequency of twinning for identicals, just as it can in fraternals. There is so much more research to be done, that we have only scratched the surface of this, as you can see. Our research is in the preliminary stages.
Hope this helps.