HONOLULU (AP) — Dr. David Sinclair’s six children grew up accustomed to him often leaving home at all hours and holidays to deliver babies.

On Wednesday, the late Honolulu obstetrician’s family members were “blown away” and “honored” to learn that a newborn he delivered in 1961 was President Barack Obama — a discovery that came after the White House released a copy of the president’s original birth certificate.

Below Obama’s mother’s signature was one which appeared to read: “David. A. Sinclair.”

“It’s my husband’s signature,” said his widow, Ivalee Sinclair, 82, from her downtown Honolulu office. She held up a copy of the birth certificate she printed from the Internet and pointed to the signature, recognizing his familiar left-handed cursive.

So-called “birthers” have questioned Obama’s birthplace, espousing theories that he was not born in the United States, possibly in his father’s native Kenya, and therefore ineligible to be president.

Obama released a short form copy of his birth certificate in 2008. Recently, potential Republican presidential candidate Donald Trump began questioning why he hadn’t ensured that the original certificate was released.

Sinclair had an obstetrics and gynecology practice in Honolulu and delivered babies all over Hawaii when Obama was born in 1961, said his son Karl Sinclair, 55, of Kailua. The doctor retired in the late 1990s and died in 2003 at 81.

“What a shocker,” said Karl Sinclair, one of six children. “It’s amazing. I’m blown away by it, quite honestly.”

They found out because one of their relatives was awake at 3 a.m. watching the news and saw the signature, said Dawn Yoshimura-Sinclair, who is married to another Sinclair son, Dr. Brian Sinclair, a neuroradiologist.

“We can attest to the fact that it is indeed dad’s signature,” Yoshimura-Sinclair said. “It’s not a common name over here. There’s no confusion that it was dad.”

Ivalee Sinclair said her husband never discussed his patients and that delivering a black child born to a white mother wouldn’t be a detail he would focus on.

“He never would have brought anything like that up,” she said. “He delivered a lot of children. I have no idea how many.”

Relatives said while they previously never made the connection, looking back it makes sense because there were few obstetricians in Honolulu at the time.

Born in Portland, Ore., Sinclair moved to Hawaii at 15 because his father was an engineer who helped build Wilson tunnel on Oahu. The doctor joined the military after hearing the Pearl Harbor bombing from his front lawn, Ivalee Sinclair said. He was an Army pilot and witnessed so much death during the war that he became a doctor so he could have a career focusing on giving life.

“I think he became a doctor because he was concerned about all the people who died in the war,” his widow said. “I think he wanted to do something to make up for that.”

Ivalee Sinclair met her future husband during trigonometry class at the University of Hawaii, where he enrolled after the war. He later went to medical school at the University of California at San Francisco, where he completed his residency.

Sinclair returned to Honolulu with his wife and children in 1960. He delivered babies mostly at what is now known as Kapiolani Medical Center for Women & Children, just a couple miles from his home and where Obama was born.

Sinclair’s widow still lives in their English tudor which features a view of the Honolulu skyline and where the Sinclairs raised their six children. The Sinclair sons said they imagine he would be thrilled one of the babies he delivered grew up to be president.

“I’m just honored and proud of my father,” Karl Sinclair said.

“I think it’s great,” said Dr. Brian Sinclair, who pursued a career in medicine because of his father. “Hawaii was a very small place back then so I guess I’m not surprised.”

Brian Sinclair graduated from the same high school as Obama but didn’t know him personally. The Sinclair family includes Obama supporters and those who didn’t vote for him, they said.

The Sinclairs hope the birth certificate will end the speculation.

“It distracts from all the issues,” Ivalee Sinclair said.

“To me, the birth certificate doesn’t lie,” Karl Sinclair said. “I think that should put everything to bed.”

Copyright 2011 The Associated Press.