People are scratching their heads after a US hospital posted a riddle about the age of twin boys born in November.
The twins were born 31 minutes apart, yet the second born is older than the first - at least on paper, accoridng to The Sun.
The confusing occurence can be easily explained.
Samuel Peterson was born on Sunday, November 6, 2016 at 1.39am.
He was followed by his twin brother Ronan 31 minutes later at what would have been 2.10am.