The chances were one in a million.
However, a British couple has given birth to a set of twins with different skin colours!
The baby girls, Myla and Anaya, have received the qualities of both parents - one of whom is mixed race.
Hannah Yarker, 20, has a largely white heritage, while her partner Kyle Armstrong, 24, is mixed race.
Little Myla was born with her daddy's looks, while Anaya took after mum - and they could not be more excited by their unexpected delivery.
"We couldn’t believe it. Kyle and I told all of our relatives and friends, ‘We’ve got one of each!’" Hannah told The Sun.
While the babies are now 10-months-old, Hannah says it took a while for them to notice the stark difference in their appearance.
"At first, both the girls had a purple tone to their skin, but they looked darker so I assumed they'd both taken after Kyle," Hannah said.
"But after two weeks, it was clear Myla takes after her dad with dark skin, brown eyes and brunette locks, while Anaya is more of a mummy's girl with a pale complexion, fair hair and light eyes."
Now, Hannah says her girls are always turning heads.
"I can't walk down the aisle at the supermarket without getting stopped. People always comment, 'are they both yours?', 'are they sisters', 'are they related?'"
Unlike identical twins, non-identical twins are born from two separate eggs - with two separate genetic codes. However, the chance of one white and one bi-racial parent giving birth to mixed twins is very rare - in fact, the odds are one in a million.