BOSTON -- The Fourth of July may be the official birthday of the United States, but the birth date also belongs to four Massachusetts boys who all belong to the same family, including twins born on this most recent Independence Day.

The Mahoney twins weren't due until July 14, but when their mother, Edina Mahoney, 30, of North Reading, started having contractions during July 4th celebrations, she underwent an emergency C-section at Brigham and Women's Hospital.

Now, twins Michael Jr. and Joseph join both their father, Michael, 51, a Lynn attorney, and their big brother, Paul, 17, in sharing a July 4 birthday.

"You don't have to worry about who's born when, that's for sure," Michael Mahoney said.

All the Mahoney boys, including Paul, were born earlier than expected, but Edina said the matching birthdays were a complete coincidence.

"If you’re pregnant, or you know something about hospital policies, you know you can't schedule a C-section on holidays," she said.

Paul said he didn't expect to add two more to the family birthday, calling it "pretty crazy."

"I'm sharing my birthday with all these guys, so it takes a little bit off of me, but I don’t really care," he said. "It's cool."

The patriotic gene did not extend to the women in the family. Another sibling, Lily, is 3 years old but she was born in December.