One set of identical twins marrying another set of identical twins, on the other hand, is a fairly rare occurrence. It is estimated that only around 250 of these so called quaternary marriages exist worldwide.
One such marriage had local folk in the eastern Chinese town of Yiwu confused. The Zhanghua couple appeared to have amazing stamina when it came to running their family restaurant. They opened for business at 6am and appeared to work until 3am the following morning when the shop closed.
The 21 hour a day couple earned themselves the nickname, "the robot couple," for their apparent super human endeavours.
Recently, however, the couple revealed that they were actually four people who ran the restaurant in shifts, but because both couples looked identical, nobody noticed the shift change.
