You know those riddle games: If a train is going at 100mph, then changes bridges, and the passenger in the red hat moves seats, how long is a piece of string?

Well, we have a new one.

There's a new pair of twins. Baby A was born first. But Baby B is older.

How does that work?

For new parents Emily and Seth Peterson, daylight saving time made the birth of their twins even more confusing.

Baby A (a.k.a. Samuel) was born at 1:39am on Sunday November 6, 2016. Baby B (a.k.a. Ronan) came into the world 31 minutes later, at 2:10am.

Except by then, daylight saving time kicked in, putting Ronan's formal birth time back to 1:10am, ahead of his brother.

And because the hospital is legally required to give the "actual birth time", it means Ronan is older.

"It literally took me a day to wrap my head around it," Emily told ABC News. "I didn't realize it was quite that big of a deal until my nurse turned around and said 'I've been working here 40 years and haven't seen anything like that.'"

Cue a few decades of sibling rivalry—or at the very least, a great dinner party conversation starter.