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Jaxon and Kaiden

Meet the Multiples: Photo Gallery of Twins and Multiples

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Updated April 21, 2010

Jaxon and Kaiden

Jaxon and Kaiden are one year old twin boys enjoying the warm weather on Easter Sunday.

Photo reprinted with permission of Tanya.

Jaxon and Kaiden were one years old when this picture was taken of them enjoying a sunny Easter Sunday in their wagon.

Although the boys look a lot alike, their zygosity has not been confirmed. Zygosity -- the more scientific term for classifying whether twins are identical or fraternal -- is not defined by how twins look, but rather refers to how twins form. Identical (monozygotic) twins form from a single, fertilized egg, thus they share the same DNA and often have very similar appearances. Fraternal (dizygotic) twins form from two separate eggs, fertilized by two different sperm. They may resemble each other, like any other brothers or sisters, but because they have their own individual DNA composition, they don't share the remarkable similarities common to monozygotics.

Often, the only way to know for sure is to undergo zygosity testing which compares samples of DNA from each individual. So, without the confirmation of such testing, many twins never really know their zygosity.

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