Doctors say it is an extremely rare occurrence, but it is possible if genes combine in a certain way.

The twin boys, named Ryan and Leo, are the offspring of a mixed-race couple.

The mother, Florence, hails from Ghana in western Africa, and dad, Stephan, is from Potsdam in Germany.

"Ryan came first, and everything was as usual," said the hospital's doctor, Birgit Weber. "But when Leo was born, I couldn't believe my eyes."

"Both kids have definitely the same father," the doctor added.