One day Kerry celebrated her birthday.
Two days later her older twin brother, Terry, celebrated his birthday.
How can this be, assuming that the difference in twins' ages can be a few minutes, but not over an hour?
Terry, the older twin, was born EAST of the International Date Line (IDL) on 1 March
Kerry, the younger twin, was born WEST of the IDL on 28 February.
They were both born on a non-leap year.
Therefore, on a leap year Kerry celebrated her birthday two days before her older twin Terry.