Via the Daily Mail:
bq.. Remee, who weighed 5lb 15oz, was blonde and fair skinned. Her sister Kian, born a minute later weighing 6lb, was black.
Both Kylie and her partner Remi Horder, 17, are of mixed race. Their mothers are both white and their fathers are black. According to the Multiple Births Foundation, baby Kian must have inherited the black genes from both sides of the family, whilst Remee inherited the white ones. [...]
Skin colour is believed to be determined by up to seven different genes working together.
The odds against of a mixed race couple having twins of dramatically different colour are a million to one.