Bruce Jenner: 'My brain is much more female than male'

— -- Bruce Jenner said that he is transitioning to become a woman in an interview broadcast Friday night.

"Yes. For all intents and purposes, I'm a woman," Jenner said when asked if he is a woman by ABC News' Diane Sawyer on "20/20."

Jenner added: "I was not genetically born that way. As of now -- I have all the male parts and all that kind of stuff...we still identify as female. And that's very hard for Bruce Jenner to say. Because why? I don't want to disappoint people."

Jenner also told Sawyer: "My brain is much more female than it is male. It's hard for people to understand that. But that's what my soul is."

Jenner, 65, won the 1976 Olympic decathlon, setting a world record and making him an international sports star. Jenner later became an actor in a number of TV movies, a race car driver (winning the 12 Hours of Sebring race in 1986) and a successful businessman. Jenner married his third wife, Kris Kardashian, in 1991 and became part of the E! network series "Keeping Up With The Kardashians" in 2007 (Kris and Bruce Jenner were divorced in December 2014).

Jenner has six biological children -- Burt, Cassandra, Brandon, Brody, Kendall and Kylie -- and four step children -- Kourtney, Kim, Khloe and Rob Kardashian. He said he told them, and his mother, recently. His ex-wives and sister were the only ones who previously knew. 

During the interview, Jenner referred to himself using male pronouns. ABC News said on its website that it chose to follow his lead, though he also referred to himself as "Bruce" and "her."

"I look at it this way -- Bruce always telling a lie," he told Sawyer. "He's lived a lie his whole life about who he is. And I can't do that any longer," Jenner said.

Jenner was asked if there was a publicity part of the decision to talk so publicly. He laughed, then become serious.

"What I'm doing is going to do the world some good," Jenner said. "And we're going to change the world ... I really firmly believe that."