This classic riddle says two children were born on the same day, in the same year, to the same parents — but they are not twins. How is that possible?
The answer is: they are two members of a set of triplets, quadruplets, or another multiple birth.
The wording only says that the two children are not twins. It never says there were only two babies born that day. If three children were born together, any two of them would share the same birthday and parents, but they would be triplets rather than twins.
The riddle works because most people automatically assume there are only two children involved. Once you remove that assumption, the solution is straightforward.
