Although twins are the same age, the question of who was born first is one that keeps cropping up. Mere minutes can make the difference between being the younger twin and the older twin, but someone has to be born first.
But for twin boys born in Massachusetts, US, daylight savings has complicated matters.
It all started when Emily Peterson gave birth to her twin sons in the early hours of November 6 at Cape Cod Hospital.
The first twin, Samuel, was born at 1.39am – not long before 2am, the clocks were turned back an hour for daylight savings.
The second twin, Ronan, arrived 31 minutes later. However, as the clocks had been turned back, his time of birth was recorded as 1.10am, officially – at least on paper – making him the older twin.
Speaking to ABC News, Peterson said that it took her and husband Seth a while to get used to it.
"My husband was the first to say it: 'Here's a riddle for you!'" she said.
"It literally took me a day to wrap my head around it. 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.'"
Michael Lauf, president and CEO of Cape Cod Healthcare, told the ABC that although it might seem ridiculous, they had a legal obligation to record the correct time.
"The Peterson twins' birth story was a remarkable occurrence," he said.
"Our veteran maternity nurse, Deb Totten, said it was the first time she has seen it in more than 40 years of nursing," he added.
"It's a pleasure to have such a positive story at our hospital about a wonderful young couple who will have a great tale for their sons."
Samuel and Ronan Peterson have now gone home to join their big sister Aubrey, who will no doubt remind them that she is the true firstborn of the family.
But the twins do have an interesting birth story. "I personally think it's kind of cool that one's 'older' and one's born first," Peterson said.
"Hopefully they're not going to be fighting over it for the rest of their lives."