Then, five years ago, a group called the Yes Institute, which teaches students about gender identity and sexual orientation in an effort to prevent suicide, came to his children’s school, and he observed. He was fascinated; still searching for clues to his unhappiness, he flew to the institute, in Miami. There, watching a clip of Oprah Winfrey interviewing an 8-year-old who was born a girl but had decided to live as a boy, he had a revelation.

“My jaw dropped, because I could have been that child,” he said.

At first, he was daunted by the prospect of confronting his family with another drastic change. But within a few months, he said, he knew that he wanted to begin exploring a more masculine identity.

“This was an opportunity to take off the gorilla suit I felt I’d been wearing all my life and really be myself,” he said.

Shortly after he made his decision in 2009, he was elected chairman of Community Board 7. At his first meeting, he told the board about his transition and received support, he said.

Much harder were the conversations with his son and daughter, now 18 and 15, although he said that they, too, had been understanding.

“We have had very deep conversations and some negotiations around what makes them comfortable,” he said, adding that they could still always call him “Mom.”

Among the things Mr. Wymore said he was proudest of from his term as community board chairman, which ended in 2011, were the negotiations over the coming Riverside Center, a major mixed-use development on the Upper West Side. As a result of pressure from the board and Ms. Brewer, the developer, Extell, agreed to build a 100,000-square-foot school and contribute $17.5 million toward renovating an adjacent park.