A striking set of twins born with different skin colors - one black and one white- are speaking out on their unique 'one-in-a-million' story. 

The girls Marcia and Millie Biggs reveal that at just age 11 they are already aware of racism and are daily peppered with the question 'Are you two really twins?' 

Marcia who has fair skin, blue eyes, and blonde hair takes after her Caucasian mother while Millie who has dark skin, brown eyes, and black hair takes after her Jamaican-descent father.

Experts say that the phenomena, although unique, occur in one in 100 fraternal births.  

Their mother calls the girls a 'one-in-a-million' miracle. 

The girls shared their story of their race-defying appearances in the April issue of National Geographic. 

The twins, of Birmingham, England, were born on July 3, 2008.

Their parents, a biracial couple, said they 'didn’t give a toss' of what people might think of their interracial relationship and brought the same approach towards their mixed race children.

At first the parents thought their daughters - who they gave the mixed names of Millie Marcia Madge Biggs, the other Marcia Millie Madge Biggs - were identical as they shared similar skin tones.  

At about 10-months their skin began to change into more distinct colors. 

'The change happened with Millie first. She went darker and darker,' father Michael Biggs said to Good Morning America. 

'We never worried about it; we just accepted it,' Michael said to National Geographic.

From their infancy, the girls were scrutinized for their difference appearances. 

'When they were first born I would be pushing them in the pram, and people would look at me and then look at my one daughter and then look at my other daughter. And then I’d get asked the question: "Are they twins?"' mother Amanda said. 

She'd respond 'Yes' to which the reply would always be 'But one's white and one's black'.

'Yes. It's genes,' she said.   

She clarified that passersby were never hostile to the girls, if anything they were curious about their contrasting appearances that made them pass off as friends rather than sisters.

'As time went on, people just saw the beauty in them,' Amanda said.  

'Sometimes people don’t believe us when we say we are twins. They think we're just telling a lie,' Marcia said to Good Morning America.  

When speaking on racism the girls reveal they understand the concept quite well. 

'Racism is where somebody judges you by your color and not by your actual self,' Millie said.

Marcia said racism is 'a negative thing, because it can hurt people’s feelings.'

Although father Michael admitted he's faced racism in life he said 'it's a different time now'.

He and wife Amanda say they've never seen racist behavior towards the girls. And the girls too say they never felt it either, even when people pick apart their looks.   

'When people see us, they think that we’re just best friends. When they learn that we’re twins, they’re kind of shocked because one’s black and one’s white,' Marcia said.

Although their radical differences may seem to be the most prominent thing about them, race is actually the farthest concern from the girls' minds.

When asked on what made the two different, the girls began to talk about their different styles and favorite colors rather than fixating on skin and eye colors. 

'Millie likes things that are girlie. She likes pink and all of that. I don’t like the color pink; I’m a tomboy. People are made how they are,' Marcia said. 

Read more on dailymail.co.uk.