Identical twins Amelia and Jasmine are thought be the first black and white twins born in the UK, despite coming from the same egg.

The girls were born to mum Libby Appleby, 37, from West Rainton, County Durham who is white and her partner Tafadzwa Madzimbamuto, 40, who is black.

They are identical or monozygotic twins, meaning they developed from the same zygote, which split and formed two embryos.

Libby Appleby, 37, from West Rainton, County Durham was told she wouldn’t be able to tell her identical twin babies apart. But Jasmine (left) and Amelia were born with contrasting skin tones

Elder twin Amelia (right) has dark skin, black hair and brown eyes, her sister Jasmine has fair skin, blue eyes and mousey curls

Monozygotic twins are always the same sex, share identical blood groups and genetic make-up and always closely resemble each other.

There are other reported cases of non-identical twins being born with different coloured skin and eyes to mixed race couples in the UK.

But, in what is believed to be a first in this country, Amelia was born with dark skin, black hair and brown eyes while her sister Jasmine has fair skin, blue eyes and mousy curls, despite being genetically identical.

Explaining the phenomenon Dr Claire Steves from the Department of Twin Research, said that multiple genes control skin colour and while identical twins are very likely to share them completely, it is not guaranteed.

During her pregnancy, LIbby was told her unborn babies would look so similar that would need to be ‘marked with ink’ to tell them apart

When the girls were born Libby and her partner were flabbergasted, and even the doctors couldn’t believe it. The pair are thought to be the first identical twins born in the UK with different skin colour

LIbby’s twins are monozygotic, meaning they formed from the same zygote. Identical twins are always share the same sex, blood group and genetic make-up and always closely resemble each other yet Amelia (left) and Amelia had different skin colours

Dr Steves, who works at King’s College London, said that the differences in how Amelia and Jasmine look could be down to a change in the way each developed in the womb.

‘However, an exception might be when a change in one of these genes that control skin colour happens after the twins separate in very early development – so called somatic mutation,’ she said.

‘Alternatively, sometimes markers on the DNA which influence the extent to which the DNA is expressed can be different in the twins.

‘We do have some evidence that skin colour is subject to this kind of “epigenetic” control.

‘Lastly, if the twins have been exposed to different environments, they may differ in skin colour due to this – for example if one has had greater sun exposure or has developed a condition where the pigmented cells are affected, which may happen to one just by chance.

An ultrasound scan of identical twins Jasmine and Amelia. Dr Claire Steves from the Department of Twin Research explained that the difference in the girls’ skin colour could be explained by the fact that sometimes markers on the DNA which influence the extent to which the DNA is expressed can be different in the twins

Dr Steves, who works at King’s College London, said that Amelia and Jasmine could look so different if there was a change in the way each developed in the womb very early on

‘Despite these possibilities which might explain this intriguing phenomenon, the vast majority of identical twins have very similar skin colouring and this case is very unusual indeed.’

During her pregnancy, Libby was told by medics that her unborn babies would look so similar that would need to be ‘marked with ink’ to tell them apart.

Despite their contrasting skin tones, the siblings are genetically identical and are thought to be first of their kind in the country.

‘When they were born, we were flabbergasted, even the doctors couldn’t believe it,’ Libby said. ‘They look like they’re different races.

The mum says strangers assume the twins – who have just celebrated their first birthday – are step-sisters

Blue-eyed Amelia takes after her mum, with blue eyes and fair skin

A sample of Libby’s placenta confirmed the twins are 100 per cent genetically identical, despite them looking nothing alike

‘Amelia is the spitting image of her dad, while Jasmine is a mini version of me.’

The mum says strangers assume the twins – who have just celebrated their first birthday – are step-sisters.

She added: ‘We get a lot of funny looks when we tell people the girls are actually identical.’

HOW DO TWINS FORM?

Identical twins occur when a single egg is fertilised then splits into two – or, very rarely, three or more – creating identical babies with the same genes, physical features and sex.

Skin colour is believed to be determined by up to seven different genes working together.

If a parent is of mixed race, their eggs or sperm will contain a mixture of genetic codes for both black and white skin.

However, if both the egg and sperm contain all white genes, the baby will be white. And if both contain just the versions necessary for black skin, the baby will be black.

The chances of giving birth to non-identical twins with different skin tones is around a million to one. However, they come from separate eggs, and therefore inherit different genes.

Libby and partner of three years, an electrical engineer, found out she was pregnant in June 2014.

Three months later they were told it was twins and medics at University Durham Hospital warned they would be so identical they would be difficult to tell apart.

Libby said medics ‘gasped’ when they delivered the twins.

Libby added: ‘We put them next to each other in a cot and couldn’t believe how different they were.

‘Amelia was so much darker than Jasmine, they barely even looked related.

‘Doctors told us the chances of conceiving mixed race twins are one in a million.

‘We were thrilled they were so unique.’

A sample of Libby’s placenta confirmed the twins are 100 per cent genetically identical, despite them looking nothing alike.

She said: ‘I don’t blame strangers for thinking they aren’t sisters, because they do look nothing alike.

‘The girls are just noticing the difference in their skin colour now.

‘But they’re so wonderful and unique.

‘Looking back, it’s funny that we were worried we’d never tell them apart.’