10 Amazing Facts About Identical Twins

Reviewed by Terri Forehand RN
twin girls in headbands

As one of the true wonders of this world, identical twins are a miracle of Mother Nature and genetics coming together. Seemingly in a league of their own, you might be surprised to discover that there's even more amazingness than you thought when it comes to being a twin.

1. Identical Twins Don't Always Look Alike

girls with mirrors

Contrary to popular belief, identical twins don't always look identical! Although they do come from the same egg and they also start out with the same DNA roadmap, they go through a plethora of genetic changes early in their development. This means that although they start out identical, they can end up looking a little bit different..much like two houses can look different after being built, even when they use the same blueprint.

2. They Don't Have Identical Fingerprints

Most of you reading this might presume that because an identical twin is identical, they also have the same fingerprints - but no! While they start out with identical fingerprints in utero, their fingers can touch their mother's amniotic sac between the 6th and 13th week of pregnancy, causing a change in the patterns of their fingerprints.

3. They Live Longer Than Fraternal Twins

mnature twins

Thanks to a powerhouse combination of genetics and incredibly close emotional ties, researchers at University of California, Berkeley found that identical twins can often outlive their fraternal counterparts. On average, identical twins who communicate once a month or more live even longer than identical twins who don't, as well as longer than fraternal twins, regardless of how frequent communication is. The saying ,"It's good to talk!" has never rung so true.

4. Identical Twins Have Almost Identical Brainwave Patterns

Ever wondered why identical twins seem to be able to read each other's minds? According to studies undertaken by the University of Minnesota, identical twins exhibit brainwave patterns that are similar both in shape and size, meaning how they perceive and think about things are incredibly similar as well.

5. Identical Twins Can be of Different Sexes

The world of identical twins just got even more mind-boggling! On occasion, identical twins can be of different sexes. Although they're almost always genetically identical, there have been cases where a genetic mutation may occur in development. In these cases, the Y chromosome is dropped for one twin and an extra X chromosome is added for the other. In other words, one twin may have the right combination of XX or XY while the other has XXY. This results in one normal male (XY) and one female with Turner syndrome.

6. If You Separate Identical Twins, They Still End up Similar

twins separated

In the Minnesota Study of Twins Reared Apart that was conducted over the course of 20 years, evidence was found that even when separated at an early age and raised in different environments, identical twins can often end up with shockingly similar character traits and personal preferences. When it comes to nature vs. nurture, this might indeed be another point for nature!

7. Identical Twins Get Sick Differently

Of course, when we're talking about genetic disorders, both twins would be candidates for the same disease to develop. But that doesn't always mean that they will suffer from the same illness. Environmental factors such as the different pathogens, bacteria, microbes, exposure to certain foods, and powerful emotional experiences outside the womb can alter their immune systems in different ways. This explains why one twin in an identical set may develop breast cancer, while the other one might remain healthy.

8. The Chances of Identical Twin Births Doesn't Increase With Age

You might already know that older women have an increased likelihood of fraternal twins, owing to the fact that they produce more than one egg per cycle. However this age-influenced increase doesn't apply to identical twins - only fraternal. So while there are things you can do to increase your chances of having twins, don't expect them to be identical!

9. It's Not Just About The Identical

Did you know that a new type of identical twin was identified in 2007? Well, not so much identical, as semi-identical. The twins were identical on their mother's side, but shared only half their genes on their father's side. Considering these partially identical twins are still young, we're still waiting to find out how similar they will end up!

10. Identical Twins DON'T Always Share a Placenta

Another identical twins myth has to do with the exact moment the eggs splits. If early on enough in pregnancy, the two embryos implant separately and develop individual placentas. But if the split happens later on, this is when they are more likely to share the placenta. Even if the placentas are split, however, they can often be so close together that they nearly fuse, looking as though there is only one.

The wonder of identical twins never ceases to amaze. And if you are a lucky parent of identical twins, you understand that firsthand!

10 Amazing Facts About Identical Twins