"We feel fortunate that he chose to arrive on a day already special to my mother and me," said Caitlyn, 32. The three individuals sharing the identical birth date and time are grandmother Mary Jo Peters, mother Caitlyn O'Brien, and baby Shawn O'Brien.

Jeannie Kauper, an obstetric nurse at the hospital, said the team was astonished by this remarkable coincidence. "We couldn't believe it. It felt like a destined moment," she said.

Recalling the day her daughter was born more than 30 years ago, Mary Jo said she initially hoped her daughter would have a separate birthday. However, a nurse's encouragement, "This is the best birthday gift you've ever received," changed her perspective.

Now, that happiness is multiplied as she welcomes her second "birthday gift" in her grandson.

Mary Jo Peters (left), newborn Shawn O'Brien (center), and Caitlyn O'Brien (right). UMass Memorial Health.

Mary Jo Peters (left), newborn Shawn O'Brien (center), and Caitlyn O'Brien (right). UMass Memorial Health.

Caitlyn, a mother of three, said the new arrival will certainly add "chaos" but also plenty of laughter to the family.

"Our family already has numerous members born in March, and Shawn's arrival adds even more significance to this list," she said.

Mathematicians estimate the probability of three generations in the same family (grandmother – mother – child) sharing a birthday is about one in 48 million.

Similar cases have been documented globally, but none have perfectly matched both the day and time of birth like this family.

In 2006, in Arizona, US, a woman named Andria Hundley gave birth to twins on her and her mother's birthday. In Finland, Guinness World Records documented the Veera Tuulia family as having four generations all born on 21/3. Meanwhile, the Mangi family in Pakistan currently holds the record with nine members, comprising parents and seven children, all born on 1/8.

Nhat Minh (via People)