Twins born just minutes apart in California will — once they start talking — likely have to explain why they don’t have the same birthday. Even more, the weren’t even born the same year.

Maria Esperanza Flores Rios gave birth to a set of identical twins, who came one month earlier than expected. Joaquin Ontiveros, Jr., was born at 11:58 p.m. on Dec. 31. He weighed 5 pounds, 9 ounces and was 18 inches long. His twin sister, Aitana de Jesus Ontiveros, was born at 12:16 a.m. on Jan. 1, 2018. She was 16-and-a-half inches long and weighed 4 pounds, 10 ounces, according to The Sacramento Bee.

The twins were born at the Delano Regional Medical Center in Delano, California. The doctor who delivered the children, Seyed Tamijidi, was shocked by this set of twins.

“I’ve been doing this for 35 years, and I’ve never had this before,” said Tamijidi, according to a Bakersfieldnow.com report.

How rare is it for twins to be born in separate years? The chances are one in 59,000, according to  Freakonomics report.

One pair of Williston twins, seniors Ana and Sophie Weed, were amazed by the scenario in Delano.

“It’s amazing how it happened, and allows them to have a difference with their twin,” said Ana. “I think being a twin is awesome, and if you asked Sophie I’m sure she’d agree.”

Ana stressed the “unbreakable bond” she and Sophie were born with, and will have the rest of their lives. Sophie agreed.

“Ana is my best friend,” said Sophie. “I know she always be there for me, since we’ve been through literally everything together. Being twins makes us much closer than most people and I’m fortunate for that.”