When Whitney Meyer tells strangers that her infant daughters are twins, they never believe her.

That's because Kalani and Jarani Dean were born with different skin colours, making them biracial twins.

Meyer, 25, is Caucasian and her boyfriend Thomas Dean is African-American. Jarani took after her dad, while Kalani inherited her mother's lighter complexion.

Posted by Whitney Meyer on Monday, 23 January 2017

The mother said she was immediately surprised when she saw her daughters, born in April 2016, for the first time.

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"I asked the doctor why Kalani's skin was so white!" Meyer told US Weekly.

"I couldn't figure out why she looked so different her sister."

Kalani and Jarani are fraternal twins, meaning that they developed from two different eggs that were each fertilized by a separate sperm cell.

Posted by Whitney Meyer on Wednesday, 31 August 2016

There is a 1 in 500 chance that interracial couples expecting twins will have children with different skin colours, according to the BBC.

The adorable girls are now turning heads in their hometown of Quincy, Illinois.

"No one believes they're twins," Meyer said.

"When we go out in public, people will start looking at them because I dress them identical and I can tell they're confused."

The birth of the twins is bittersweet for the couple who lost their two-year-old son, Pravyn, in a drowning accident two years ago.

Jarani - the darker skinned twin - looks identical to her late brother.

"They are my miracle babies," Meyer said of her twins. "J looks exactly like her brother did.

"When I look at pictures of J, I see Pravyn."

They pair also have an 7-year-old older brother.

Merry Christmas to my Pra Pra!! I miss you so much!! I love you more than ever. You would of been running around crazy...

Posted by Whitney Meyer on Saturday, 24 December 2016

But when it comes to her twins, Meyer said the girls' personalities couldn't be more different.

"Kalani is our loud child," Meyer said. "She is crawling everywhere and going nonstop.

"J doesn't like to move. She just wants to be held, and she loves to eat."