Marcia and Millie Biggs, both 11, looked almost identical when they were first born in July 2006, but their differences soon became apparent.
As Millie started to become darker-skinned, Marcia took on a lighter complexion, growing blonde, curly hair.
Mum Amanda Biggs, 46, from Birmingham, said even when her twin daughters were at primary school, people would get confused about whether they were related.
“I’d be picking them up after school, and the other parents would stop me and say: ‘Are they your daughters?’” the mum said.
“When I told that them that they were twins, they would always be stunned. I notice a lot of people doing double-takes.”
Marcia has inherited her mother’s fair complexion and golden brown hair, while Millie takes after dad Michael, 50, who is of Jamaican origin.
Speaking about the confusion she encounters, Biggs said: “It does get a bit irritating sometimes, when you have people stopping you in the street all the time, but then I remember how beautiful they are and how lucky I am to have them, and the irritation goes away.
“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.”
The mum continued: “Other than the differences in skin tone, they look almost exactly the same. They are both absolutely beautiful, and they make me proud everyday.
“They do absolutely everything together and they’re always making videos of themselves singing and dancing together.
“When they were younger, Millie was always quite shy, but as she’s grown up she’s become a real bossy-boots. She’s very organised and in control, and is often telling Marcia what do.
“Millie is our little princess, she loves to have clothes related to princesses and lots of dolls. She’s obsessed with the colour pink as well, just like you’d expect from a little feminine girl. Marcia’s a lot more of a tomboy.”
Biggs said: ““They are both really excited to be moving up to secondary school, because they love to learn.
“Millie is very good at maths, and Marcia has a talent for English, so it’s good that they have that bit of competition together.”
The sisters will be attending King Solomon International Business School in Aston, Birmingham, on Wednesday 7 September.
“I’ve explained to the school that despite their differences, they are twins, and hopefully that will help to overcome any awkwardness,” said Biggs.
“But people are going to be amazed by them for the rest of their lives, and I think that’s fantastic.”
Speaking about starting secondary school, Millie said: “I am excited to start. I think that it’s going to be fun to meet some new people and make lots of friends.
“My favourite lesson is maths. It makes me laugh a lot when people don’t believe that we’re twins.”
And Marcia added: “It’s going to be fun to go to a new school. The bit I’m most excited about is going to the lessons. My best friend is Millie, because she’s always been there.”