Marcia and Millie Biggs' mom has already visited their school to tell teachers the girls are in fact twins.
There’s no trouble telling these 11-year-old twins apart, as one is white and one is black.
Marcia and Millie Biggs, from Birmingham in England, looked almost identical when they were born in July 2006 but their difference in skin tone became more apparent as they aged.
Read: Twin Teens, One Black, One White, Celebrate Their Differences
As brown-eyed Millie started to become darker skinned, blue-eyed Marcia took on a lighter complexion and grew blonde, curly hair.
The twins’ mom, Amanda Biggs, is white, while their dad, Michael Biggs, is Jamaican.
"Within a few months, the changes started to happen," Michael Biggs told SWNS. "Millie started to suddenly get darker, and we thought that the same would happen to Marcia. I thought to myself: 'No problem - one black, one white.' We never worried about it, though, we just accepted it.”
Ahead of the girls' first day at secondary school this week, their parents had to explain to their teachers that they were in fact twins. Some of their teachers were shocked, and strangers are often baffled when they find out the girls are related, much less twins.
"I'd be picking them up after school, and the other parents would stop me and say: 'Are they your daughters?'” Amanda Biggs said. "When I told that them that they were twins, they would always be stunned. I notice a lot of people doing double-takes.”
Other than Marcia and Millie’s difference in skin tone, their mom says their features are quite similar.
“They look almost exactly the same. They are both absolutely beautiful, and they make me proud every day,” Amanda Biggs said. "They do absolutely everything together.”
Millie is the bossy one and loves princesses and dolls while Marcia is more of Tomboy, their parents note.
The twins are both very sociable, however.
“They're both very outgoing and positive, which is wonderful. They're great to be around, because they always make you smile,” Amanda Biggs said. "I've devoted my whole life to looking after them, and I've treasured seeing them grow up together.”
Read: 47-Year-Old Twins Are Addicted to Being Identical
Although their mother is sometimes irritated when people question if they're twins, it doesn’t seem to bother the girls much.
"It makes me laugh a lot when people don't believe that we're twins,” Millie said
Watch: Mom On Having Twins With Different Skin Tones: 'I Don't See Color In My House'