Twins of different colors were born in one millionth chance

Genetics experts say that in most cases a mixed-race woman's eggs will be a mixture of genes for both black and white skin.

However, more rarely, the eggs may contain genes for predominantly one skin colour. In this case, there were two such eggs, one with dark pigmentation genes and one fair. Clinical geneticist Dr Stephen Withers said the likelihood of a mixed-race woman having eggs that were predominantly for one skin colour was rare enough, let alone producing two of them, resulting in twins.

"It's probably a million to one," he said. "It's a terrifically rare phenomenon."