Marcia and Millie Biggs, 11, looked almost identical when they were born in July 2006.
But as Millie started to become darker-skinned, blue-eyed Marcia took on a lighter complexion – growing blonde, curly hair.
And mum, Amanda, has had to warn King Solomon International Business School in Aston, Birmingham, where they will start secondary school next Thursday, that they are actually twins.
“I’ve explained to the school that despite their differences, they are twins, and hopefully that will help to overcome any awkwardness,” said the 46-year-old.
“But people are going to be amazed by them for the rest of their lives, and I think that’s fantastic.”
Marcia has inherited her mother’s fair complexion and golden brown hair, while Millie takes after dad Michael, 50, who is of Jamaican origin, with her tight dark curls and brown skin.
Amanda added: “There were a few teachers who didn’t believe them at first, but as they got to know them, they saw how similar they were.
“Other than the differences in skin tone, they look almost exactly the same. They are both absolutely beautiful, and they make me proud everyday.”
The couple both told how they are repeatedly stopped in the street when baffled passers-by catch eyes on the lovable pair.
“Even when they were at primary school, people would get confused,” said Amanda.
Although Millie was ‘quite shy’, she has turned out to be a ‘real bossy-boots’ and a ‘little feminine girl’, said Amanda, while Marcia’s a ‘bit like a tomboy’.