"I had my first emotional attraction to another girl when I was 11," Gingrich said.
Gingrich, 30, a native of Harrisburg, Pa., said her mother asked questions when she found a copy of a lesbian newsletter in her room when she was 20.
"Newt was already in Congress, " said Gingrich, a frequent speaker for the Human Rights Campaign, the largest national gay and lesbian political lobby group.
She said her home was like a shrine, with pictures of the congressman everywhere.
"My family was very proud of Newt," she said.
"Everybody in my family knew I was a lesbian, but I felt it was in my best interest to keep it quiet," Gingrich said. "I didn't want to (hurt) Newt's career, and I was afraid I would risk losing my family if it came out."
She said the media descended on her family in Harrisburg when her brother became speaker of the House.
"That was my third coming out. An Associated Press reporter interviewed me. The last thing she asked me was if I was gay. I said `yes I am,'" said Gingrich.
Gingrich, who lives in Washington, D.C., said her brother was never a big influence in her life.
"He was living in Georgia when I was born," Gingrich said. "I only saw him on holidays."
Even now, she said she sees him only a couple of times a year. "We chat on the phone sometimes," she said.
Concerning her homosexuality, she said her brother, Newt, 53, told her that "it was my life and that I a right to live it the way I wanted to."
She also said the only reason she's happy that the Republicans gained control of the House in 1994 is because it elevated her brother to speaker.
Gingrich said 85 percent of Americans questioned in voter exit polls believe a person can't be fired for being gay.
"You can be fired if you're gay or even if it's rumored that you're gay," Gingrich said.
She said gays aren't seeking special privileges, only the same constitutional protections everyone else has.