Pictured: Proud parents show off their million-to-one black and white twins

But when brothers Ryan and Leo arrived they had an extra surprise for their parents - they were born with different coloured skin.

For one twin to be black and one to be white is so rare that it is thought by medical experts to be a one in a million occurrence.

Proud parents: Florence Addo-Gerth and Stephan Gerth with their newborn twins Ryan (right) and Leo (left)

Proud parents Florence Addo-Gerth and Stephan Gerth are over-joyed by the new additions to their family, which includes 18-year-old brother Randy.

Mother Florence, 35, hails from Ghana, west Africa while father Stephan is German. 

Stephan, 40, said that although the couple were surprised by the children's different colourings the most important  thing was that the babies were healthy.

Big yawn: Ryan (left) and Leo enjoy a nap, oblivious to the sensation their births have caused

The infants caused a sensation at the Sana Hospital in Lichtenberg, Germany, where they were born on Friday last week, with guests crowding around to greet the new arrivals.

And it is not only their skin colours that are different - the twins are already revealing opposing personalities.

Light-skinned Ryan is described as a 'spirited' baby, while laidback brother Leo is a lot calmer.

Senior doctor Birgit Weber, who helped deliver the tots by ceasarean section, said that in 20 years of practice this was the first time she had seen differently coloured twins.