500/1 odds make THESE rainbow babies exceptionally unique

Twin girls from Illinois have celebrated their first birthday together and the photographs are captivating.

Kalani and Jarani Dean are rainbow babies, born after the death of their brother Pravyn.

But they are also biracial twins, otherwise known as fraternal twins.

This means Kalani has light skin and blue eyes, while twin sister Jarani has dark skin and brown eyes.

Their mum, Whitney, is Caucasian while their dad, Tomas, is African-American which partially explains the reason their skin colour differs.

Fraternal twins come about when the twins begin their journey as separate fertilised eggs, instead of being from the same egg and splitting as do regular twins.

Therefore, each baby inherited a different combination of genes from both their mum and dad, making it possible for couples of different racial identities to have children with different skin colour.

However, the odds of this happening are significantly low, with only a 500/1 chance of it actually occurring.

And that’s what makes these two cuties extra special, so when Mary-Kathryn Nourse of Elite Photography had a photoshoot featuring the girls, it was bound to be beautiful.

The snap depicts the girls in a make-shift tub wearing flower crowns, and flowers circling the tub. 

The flowers are extra special though – they're all the colours of the rainbow. 

This really is a special one.