Olympic gold medalist Dominique Moceanu discovers another sister

(AP) -- Olympic gold medalist Dominique Moceanu discovered at 26 that she had another sister, given up for adoption at birth.

In her new memoir, "Off Balance," scheduled to be released Tuesday, Moceanu tells of receiving a letter and some photos in December 2007 from a 20-year-old woman who looked strikingly like the gymnast's younger sister, Christina. The package came two weeks before Moceanu had her first child, Carmen.

"It was the biggest bombshell of my life," Moceanu said in an interview with ABC's "20/20" that is scheduled to air Friday night. "I had this sister that was born who was given up for adoption, and I never knew it."

Moceanu said she confronted her parents, Dumitru and Camelia, who told her the girl had been born with serious medical problems that would require expensive treatment. The Romanian immigrants had little money, and doctors recommended she be given up for adoption. The young woman has no legs, Moceanu said.

Five years later, Moceanu and the woman have met many times.

"The tones in our voices, our handwriting, the way we laugh and chuckle. It's mind-blowing," Moceanu said.

The woman was not identified on the ABC website, and advance copies of Moceanu's book were not available.

Moceanu was 14 when she and the rest of the "Magnificent Seven" won the gold medal in Atlanta. They remain the only U.S. women's team to win the Olympic title.

Copyright 2012 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.