99% Monozygotic

When Elise and Charlotte were born, we did not know if they were identical or fraternal twins. It was tough to tell at first because they differed in their size, and they just look like cute babies! We wanted to find out - for curiosity, and some practical reasons. We ordered a DNA test kit from a company and sent in cheek swabs from both of them. About 10 days later we got the news! 99% probability that they are monozygotic (identical) twins! Here are some facts about identical twins:

• They share the same nuclear DNA, but may differ in their mitochondrial DNA.
• Identical twins do not "run in the family". This makes sense for us because ours are the first twins!
• Fraternal twins are twice as common as identical twins.
• The odds of identical twins is about 3/1000.
• Their fingerprints are different because fingerprints are a function of phenotype, not genotype.
• Since they are a genetic match, they can give blood or organs to each other, should the need arise.
• My twin girls, Elise and Charlotte, are the most beautiful identical twins in the world.