Photo of biracial twins in Illinois goes viral after mom shares on Facebook

Fraternal twins are known for having distinct physical features, and in some cases those differences are more noticeable than others. But a pair of Quincy, Illinois, twins are going viral for their more-distinct-than-usual appearances – one appears black and the other, white.

KHQA.com reported that Kalani Dean and Jarani Dean, who are 9 months old, are biracial twins. Their mother, Whitney Meyer, posted a photo of the girls on KHQA’s Facebook wall on Monday morning. Whitney is white, while her partner, Tomas Dean, is black.

"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!” Whitney told KHQA. “But sure enough they're biracial twins!"

Although a small number of genes are responsible for an individual’s skin color, there is a one in 500 chance that twins will have different skin colors, the BBC reported.

All fraternal twins, including Kalani and Jarani, are formed with separate eggs fertilized by two different sperm cells.

Like all twins, the girls are also distinct in ways besides their skin color. Whitney told KHQA that Kalani, who has darker skin than her sister, is energetic and already crawling, while Jarani prefers eating and hasn’t yet expressed an interest in crawling.