What is a mirror image twin?

_Elsa_

“Dad come see some interesting information that I am finding online,” Tiffi says. “Elsa wrote a story last week about our Nutcracker finding out that he has an identical twin.  So, me being curious, I went online to read all about identical twins. Did you know that there are 7 different kinds of twins? I thought there was just identical and fraternal, but you have to read this!” 

Mr. Toffee finds all of this information intriguing. He is fascinated with the information that he is seeing about mirror twins. 

Mirror image identical twins have reverse asymmetric features. About 25 percent of identical twins develop directly facing each other, meaning they become exact reflections of one another. According to About.com, "they may be right- and left-handed, have birthmarks on opposite sides of their body, or have hair whorls that swirl in opposite directions." This occurs when the twins split from one fertilized egg more than a week after conception. (Info from here)

The major characteristics of mirror imaged twins are they usually have opposite features such as hair whirls, left/right handedness, mirror twins can have the same eye conditions in opposite eyes, opposite teeth eruption, some mirror image twins cross their legs opposite to each other and in extreme cases, twins can even have reversed organs. Situs inversus is a genetic condition in which the organs in the chest and abdomen are positioned in a mirror image from their normal positions. For example, the left atrium of the heart and the left lung are positioned on the body’s right side. In the abdominal cavity, the liver is positioned mostly on the left side instead of the right. And the stomach is on the right side of the body instead of the left. (Info from here)

Both Tiffi and her father cannot imagine mirror twins and the genetic situs inversus. That has to be very rare. Mr. Toffee has to leave and head on over to his store. 

“Have a good day Tiffi,” he says. “I will read more about this when I get home later today.”

Let's continue with the next part of our story – Twin Days Festival

Start at the beginning – Tiffi co-authors another story – It’s a twin thing! (Sequel to "The story of Jean-Luc") 

If you have not yet read the story of how Nutcracker learns that he has a twin, then please read The story of Jean_Luc first.