Story highlights Striking biracial twins are example of biological rarity

Kalani has light skin; blue eyes; Jarani has dark skin, brown eyes -- and they are twins

(CNN) These adorable baby girls are Kalani and Jarani Dean. Despite their different appearances -- Kalani has light skin and blue eyes, and Jarani has dark skin and brown eyes -- they are actually twins.

The girls' parents are Whitney Meyer and Tomas Dean, from Quincy, Illinois . Meyer has been posting pictures of the unique pair since they were born last April.

The couple obviously couldn't believe their luck.

"At first when they were born, I wanted to believe it but it's so rare I didn't think it'd happen to my twins!" Meyer told CNN affiliate KHQA . "But sure enough they're biracial twins!"

Meyer is white and Dean is black, which explains part of this phenomenon. The twins are dizygotic, which is just the scientific term for fraternal twins . So each baby girl started out as a separate fertilized egg (monozygotic, or identical twins, start off from the same egg and then divide).

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